diff --git a/i18n/english.yml b/i18n/english.yml
index 182450331..ccda84b77 100644
--- a/i18n/english.yml
+++ b/i18n/english.yml
@@ -58,6 +58,9 @@ components:
     deployments: Deployments
     projects: Projects
     root: Explore
+  CalendarSelect:
+    exceptionBasedCalendar: (Exception based calendar)
+    selectCalendar: " Select calendar..."
   ConfirmModal:
     cancel: Cancel
     ok: OK
@@ -327,6 +330,9 @@ components:
     createStop: Right-click a location on map to create a new stop
     editSchedules: Edit schedules
     name: Name
+  ExceptionCalendarSelector: 
+    selectCalendar: Select calendar...
+    unnamedDefault: "[unnamed]"
   ExceptionDate: 
     addRange: Add range
     dateRemoved: ⓘ Date has been removed. Date entered is already included in an existing range or single date!
@@ -1165,6 +1171,24 @@ components:
       patterns: "%num% Patterns"
       stops: "%num% Stops"
       trips: "%num% Trips"
+  ScheduleExceptionForm:
+    addDate: Add date
+    customServiceID: Custom service ID
+    dates: Dates
+    exceptionBasedService: Exception Based Service
+    exceptionName: Exception name*
+    noDatesSpecified: No dates specified
+    noService: No Service
+    onTheseDates: On these dates*
+    ranges: Ranges
+    runFollowing: "Run the following schedule:"
+    selectCalendar: Select calendar to run*
+    selectCalendarToAdd: "Select calendars to add (optional):"
+    selectCalendarToRemove: "Select calendars to remove (optional):"
+    selectExemplar: -- Select exception type --
+    swapAddOrRemove: Swap, add, or remove
+    thanksgivingDay: Thanksgiving Day
+    unnamedDefault: "[unnamed]"
   SelectFileModal:
     ok: OK
     cancel: Cancel
@@ -1469,6 +1493,8 @@ components:
     save: Save
   Validation:
     agencyRequired: Field must be populated for feeds with more than one agency.
+    conflictingServiceId: Service ID already exists in a standard calendar!
+    customServiceId: Custom service ID
     dateServiceIdCombinationDuplicate: Date (%exceptionDate%) and Service ID (%serviceId%) combination cannot appear more than once for all exceptions.
     idMustBeUnique: Identifier must be unique.
     idRequired: Identifier is required if more than one agency exists.
diff --git a/i18n/german.yml b/i18n/german.yml
index 788a40925..12d8c2201 100644
--- a/i18n/german.yml
+++ b/i18n/german.yml
@@ -58,6 +58,9 @@ components:
     deployments: Deployments
     projects: Projekte
     root: Erkunden
+  CalendarSelect:
+    exceptionBasedCalendar: (Exception based calendar)
+    selectCalendar: " Select calendar..."
   ConfirmModal:
     cancel: Abbrechen
     ok: OK
@@ -336,6 +339,9 @@ components:
       auf eine Örtlickeit in der Karte
     editSchedules: Abfahrzeiten erstellen
     name: Name
+  ExceptionCalendarSelector: 
+    selectCalendar: Select calendar...
+    unnamedDefault: "[unnamed]"
   ExceptionDate: 
     addRange: Add range
     dateRemoved: ⓘ Date has been removed. Date entered is already included in an existing range or single date!
@@ -1167,6 +1173,24 @@ components:
       patterns: "%num% Patterns"
       stops: "%num% Stops"
       trips: "%num% Trips"
+  ScheduleExceptionForm:
+    addDate: " Add date"
+    customServiceID: Custom service ID
+    dates: Dates
+    exceptionBasedService: Exception Based Service
+    exceptionName: Exception name*
+    noDatesSpecified: No dates specified
+    noService: No Service
+    onTheseDates: On these dates*
+    ranges: Ranges
+    runFollowing: "Run the following schedule:"
+    selectCalendar: Select calendar to run*
+    selectCalendarToAdd: "Select calendars to add (optional):"
+    selectCalendarToRemove: "Select calendars to remove (optional):"
+    selectExemplar: -- Select exception type --
+    swapAddOrRemove: Swap, add, or remove
+    thanksgivingDay: Thanksgiving Day
+    unnamedDefault: "[unnamed]"
   SelectFileModal:
     cancel: Abbrechen
     ok: OK
@@ -1473,6 +1497,8 @@ components:
     save: Speichern
   Validation:
     agencyRequired: Field must be populated for feeds with more than one agency.
+    conflictingServiceId: Service ID already exists in a standard calendar!
+    customServiceId: Custom service ID
     dateServiceIdCombinationDuplicate: Date (%exceptionDate%) and Service ID (%serviceId%) combination cannot appear more than once for all exceptions.
     idMustBeUnique: Identifier must be unique.
     idRequired: Identifier is required if more than one agency exists.
diff --git a/i18n/polish.yml b/i18n/polish.yml
index f47e6518f..ca78d076d 100644
--- a/i18n/polish.yml
+++ b/i18n/polish.yml
@@ -58,6 +58,9 @@ components:
     deployments: Wdrożenia
     projects: Projekty
     root: Eksploruj
+  CalendarSelect:
+    exceptionBasedCalendar: (Exception based calendar)
+    selectCalendar: " Select calendar..."
   ConfirmModal:
     cancel: Cancel
     ok: OK
@@ -333,6 +336,9 @@ components:
     createStop: Right-click a location on map to create a new stop
     editSchedules: Edit schedules
     name: Name
+  ExceptionCalendarSelector: 
+    selectCalendar: Select calendar...
+    unnamedDefault: "[unnamed]"
   ExceptionDate: 
     addRange: Add range
     dateRemoved: ⓘ Date has been removed. Date entered is already included in an existing range or single date!
@@ -1153,6 +1159,24 @@ components:
       patterns: "%num% Patterns"
       stops: "%num% Stops"
       trips: "%num% Trips"
+  ScheduleExceptionForm:
+    addDate: " Add date"
+    customServiceID: Custom service ID
+    dates: Dates
+    exceptionBasedService: Exception Based Service
+    exceptionName: Exception name*
+    noDatesSpecified: No dates specified
+    noService: No Service
+    onTheseDates: On these dates*
+    ranges: Ranges
+    runFollowing: "Run the following schedule:"
+    selectCalendar: Select calendar to run*
+    selectCalendarToAdd: "Select calendars to add (optional):"
+    selectCalendarToRemove: "Select calendars to remove (optional):"
+    selectExemplar: -- Select exception type --
+    swapAddOrRemove: Swap, add, or remove
+    thanksgivingDay: Thanksgiving Day
+    unnamedDefault: "[unnamed]"
   SelectFileModal:
     cancel: Cancel
     ok: OK
@@ -1450,6 +1474,8 @@ components:
     save: Save
   Validation:
     agencyRequired: Field must be populated for feeds with more than one agency.
+    conflictingServiceId: Service ID already exists in a standard calendar!
+    customServiceId: Custom service ID
     dateServiceIdCombinationDuplicate: Date (%exceptionDate%) and Service ID (%serviceId%) combination cannot appear more than once for all exceptions.
     idMustBeUnique: Identifier must be unique.
     idRequired: Identifier is required if more than one agency exists.
diff --git a/lib/editor/actions/editor.js b/lib/editor/actions/editor.js
index 589feab5d..b83e5ad06 100644
--- a/lib/editor/actions/editor.js
+++ b/lib/editor/actions/editor.js
@@ -513,6 +513,10 @@ export function fetchBaseGtfs ({
             # Fetch dates to ensure we can do validation in the UI
             # (avoid duplicate dates).
             dates
+            # Fetch exemplar for display of exception based service in calendar select
+            exemplar
+            # Fetch custom_schedule for proper service_id in exception based services
+            custom_schedule
           }
           stops (limit: -1) {
             id
diff --git a/lib/editor/components/ScheduleExceptionForm.js b/lib/editor/components/ScheduleExceptionForm.js
index d15a615fa..541f06a9c 100644
--- a/lib/editor/components/ScheduleExceptionForm.js
+++ b/lib/editor/components/ScheduleExceptionForm.js
@@ -17,6 +17,7 @@ import toSentenceCase from '../../common/util/text'
 import {getRangesForDates} from '../../common/util/exceptions'
 import {EXCEPTION_EXEMPLARS} from '../util'
 import {getTableById} from '../util/gtfs'
+import {getComponentMessages} from '../../common/util/config'
 import type {ServiceCalendar, ScheduleException} from '../../types'
 import type {EditorTables} from '../../types/reducers'
 import type {EditorValidationIssue} from '../util/validation'
@@ -37,6 +38,8 @@ type SelectOption = {
 }
 
 export default class ScheduleExceptionForm extends Component<Props> {
+  messages = getComponentMessages('ScheduleExceptionForm')
+
   _onAddDate = () => {
     const {activeComponent, activeEntity, updateActiveGtfsEntity} = this.props
     const dates = [...activeEntity.dates]
@@ -87,12 +90,23 @@ export default class ScheduleExceptionForm extends Component<Props> {
     })
   }
 
+  _onCustomScheduleChange = (evt: SyntheticInputEvent<HTMLInputElement>) => {
+    const {activeComponent, activeEntity, updateActiveGtfsEntity} = this.props
+    updateActiveGtfsEntity({
+      component: activeComponent,
+      entity: activeEntity,
+      props: {custom_schedule: evt.target.value}
+    })
+  }
+
   _renderExceptionExemplars (exemplar: string, value: number): string {
     switch (value) {
       case EXCEPTION_EXEMPLARS.SWAP:
-        return 'Swap, add, or remove'
+        return this.messages('swapAddOrRemove')
       case EXCEPTION_EXEMPLARS.NO_SERVICE:
-        return toSentenceCase(exemplar.replace('_', ' '))
+        return this.messages('noService')
+      case EXCEPTION_EXEMPLARS.EXCEPTION_SERVICE:
+        return this.messages('exceptionBasedService')
       default:
         return toSentenceCase(exemplar)
     }
@@ -147,11 +161,11 @@ export default class ScheduleExceptionForm extends Component<Props> {
             validationState={this._checkValidation('name')}
           >
             <ControlLabel>
-              <small>Exception name*</small>
+              <small>{this.messages('exceptionName')}</small>
             </ControlLabel>
             <FormControl
               value={name || ''} // If name not given, provide empty string to override FormControl state.
-              placeholder='Thanksgiving Day'
+              placeholder={this.messages('thanksgivingDay')}
               onChange={this._onNameChange} />
           </FormGroup>
           <FormGroup
@@ -161,14 +175,14 @@ export default class ScheduleExceptionForm extends Component<Props> {
             validationState={this._checkValidation('exemplar')}
           >
             <ControlLabel>
-              <small>Run the following schedule:</small>
+              <small>{this.messages('runFollowing')}</small>
             </ControlLabel>
             <FormControl
               componentClass='select'
               value={hasExemplar ? exemplar : ''}
               onChange={this._onExemplarChange}>
               <option value='' disabled>
-                -- Select exception type --
+                {this.messages('selectExemplar')}
               </option>
               {Object.keys(EXCEPTION_EXEMPLARS)
                 .map(exemplar => {
@@ -186,7 +200,7 @@ export default class ScheduleExceptionForm extends Component<Props> {
           </FormGroup>
           {exemplar === EXCEPTION_EXEMPLARS.CUSTOM
             ? <ExceptionCalendarSelector
-              label={'Select calendar to run*'}
+              label={this.messages('selectCalendar')}
               id={`custom_schedule`}
               value={customSchedule}
               onChange={this._onCalendarChange}
@@ -197,13 +211,13 @@ export default class ScheduleExceptionForm extends Component<Props> {
             ? (
               <div>
                 <ExceptionCalendarSelector
-                  label={'Select calendars to add (optional):'}
+                  label={this.messages('selectCalendarToAdd')}
                   id={`added_service`}
                   value={addedService}
                   onChange={this._onCalendarChange}
                   calendars={this._filterByList(calendars, removedService)} />
                 <ExceptionCalendarSelector
-                  label={'Select calendars to remove (optional):'}
+                  label={this.messages('selectCalendarToRemove')}
                   id={`removed_service`}
                   value={removedService}
                   onChange={this._onCalendarChange}
@@ -212,6 +226,18 @@ export default class ScheduleExceptionForm extends Component<Props> {
             )
             : null
           }
+          {exemplar === EXCEPTION_EXEMPLARS.EXCEPTION_SERVICE &&
+            <FormGroup className={`col-xs-12`} validationState={this._checkValidation('Custom service ID')}>
+              <ControlLabel>
+                <small>{this.messages('customServiceID')}</small>
+              </ControlLabel>
+              <FormControl
+                value={activeEntity.custom_schedule || ''} // If custom_schedule not provided yet, provide empty string to override FormControl state.
+                placeholder='Thanksgiving-custom-1'
+                onChange={this._onCustomScheduleChange}
+              />
+            </FormGroup>
+          }
           <FormGroup
             className={`col-xs-12`}
             controlId={`exception-dates`}
@@ -219,7 +245,7 @@ export default class ScheduleExceptionForm extends Component<Props> {
             validationState={this._checkValidation('dates')}
           >
             <ControlLabel>
-              <small>On these dates*</small>
+              <small>{this.messages('onTheseDates')}</small>
             </ControlLabel>
             <FlipMove
               enterAnimation='accordionVertical'
@@ -229,7 +255,7 @@ export default class ScheduleExceptionForm extends Component<Props> {
               maintainContainerHeight
               typeName={null}
             >
-              {datesAndRangesBothActive && <h6 className='exception-subtitle'>Ranges</h6>}
+              {datesAndRangesBothActive && <h6 className='exception-subtitle'>{this.messages('ranges')}</h6>}
               {ranges && ranges.map((range, index) => {
                 const startDateIndex = dates.findIndex(d => d === range.startDate)
                 const endDateIndex = dates.findIndex(d => d === range.endDate)
@@ -242,7 +268,7 @@ export default class ScheduleExceptionForm extends Component<Props> {
                     {...this.props}
                   />)
               })}
-              {datesAndRangesBothActive && <h6 className='exception-subtitle'>Dates</h6>}
+              {datesAndRangesBothActive && <h6 className='exception-subtitle'>{this.messages('dates')}</h6>}
               {parsedDates && parsedDates.map((date, index) => {
                 const dateIndex = dates.findIndex(d => d === date)
                 return (
@@ -256,7 +282,7 @@ export default class ScheduleExceptionForm extends Component<Props> {
               })}
             </FlipMove>
             {(!parsedDates || parsedDates.length === 0) && (!ranges || ranges.length === 0) &&
-              <div>No dates specified</div>
+              <div>{this.messages('noDatesSpecified')}</div>
             }
           </FormGroup>
           <div className={`col-xs-12`}>
@@ -265,7 +291,7 @@ export default class ScheduleExceptionForm extends Component<Props> {
               disabled={this.props.validationErrors.find(el => el.field.includes('dates-'))} // Any dates validation issue blocks adding a new date
               onClick={this._onAddDate}
             >
-              <Icon type='plus' /> Add date
+              <Icon type='plus' />{this.messages('addDate')}
             </Button>
           </div>
         </Form>
@@ -283,6 +309,8 @@ type SelectorProps = {
 }
 
 class ExceptionCalendarSelector extends Component<SelectorProps> {
+  messages = getComponentMessages('ExceptionCalendarSelector')
+
   _onChange = (input: ?Array<SelectOption>) => {
     const {id, onChange} = this.props
     onChange && onChange(input, id)
@@ -295,7 +323,7 @@ class ExceptionCalendarSelector extends Component<SelectorProps> {
   })
 
   _getCalendarName = calendar => {
-    let name = '[unnamed]'
+    let name = this.messages('unnamedDefault')
     if (calendar) {
       name = calendar.description ? calendar.description : ''
       name += calendar.id ? ` (${calendar.id})` : ''
@@ -309,7 +337,7 @@ class ExceptionCalendarSelector extends Component<SelectorProps> {
       <FormGroup controlId={id} className={`col-xs-12`}>
         <ControlLabel><small>{label}</small></ControlLabel>
         <Select
-          placeholder='Select calendar...'
+          placeholder={this.messages('selectCalendar')}
           clearable
           multi
           value={value}
diff --git a/lib/editor/components/timetable/CalendarSelect.js b/lib/editor/components/timetable/CalendarSelect.js
index c2cb872cc..200f8ce7f 100644
--- a/lib/editor/components/timetable/CalendarSelect.js
+++ b/lib/editor/components/timetable/CalendarSelect.js
@@ -7,8 +7,8 @@ import Select from 'react-select'
 
 import * as activeActions from '../../actions/active'
 import {entityIsNew} from '../../util/objects'
-
-import type {Pattern, GtfsRoute, Feed, ServiceCalendar, Trip, TripCounts} from '../../../types'
+import {getComponentMessages} from '../../../common/util/config'
+import type {Pattern, GtfsRoute, Feed, ServiceCalendar, ScheduleExceptionCalendar, Trip, TripCounts} from '../../../types'
 
 type CalendarOption = {
   calendar: ServiceCalendar,
@@ -21,9 +21,10 @@ type CalendarOption = {
 }
 
 type Props = {
-  activeCalendar: ?ServiceCalendar,
+  activeCalendar: ?ServiceCalendar | ?ScheduleExceptionCalendar,
   activePattern: Pattern,
   calendars: Array<ServiceCalendar>,
+  exceptionBasedCalendars: ?Array<ScheduleExceptionCalendar>,
   feedSource: Feed,
   route: GtfsRoute,
   setActiveEntity: typeof activeActions.setActiveEntity,
@@ -32,6 +33,7 @@ type Props = {
 }
 
 export default class CalendarSelect extends Component<Props> {
+  messages = getComponentMessages('CalendarSelect')
   _optionRenderer = (option: CalendarOption) => {
     const {
       label,
@@ -49,28 +51,36 @@ export default class CalendarSelect extends Component<Props> {
       <span title={title}>
         <Icon type='calendar-o' /> {label}
         {' '}
-        <BsLabel
-          bsStyle={patternTrips ? 'success' : 'default'}
-          title={`Calendar has ${patternTrips} trips for pattern`}>
-          <Icon type='bars' /> {patternTrips}
-        </BsLabel>
-        {/** {' '}
-        <BsLabel
-          title={`Calendar has trips for ${routeCount} routes`}>
-          <Icon type='bus' /> {routeCount}
-        </BsLabel> **/}
-        {' '}
-        <BsLabel
-          title={`Calendar has ${totalTrips} trips for feed`}>
-          <Icon type='building-o' /> {totalTrips}
-        </BsLabel>
+        {/* $FlowFixMe: need to add two types of options */}
+        {option.type !== 'exception-based'
+          ? <>
+            <BsLabel
+              bsStyle={patternTrips ? 'success' : 'default'}
+              title={`Calendar has ${patternTrips} trips for pattern`}>
+              <Icon type='bars' /> {patternTrips}
+            </BsLabel>
+            {/** {' '}
+            <BsLabel
+              title={`Calendar has trips for ${routeCount} routes`}>
+              <Icon type='bus' /> {routeCount}
+            </BsLabel> **/}
+            {' '}
+            <BsLabel
+              title={`Calendar has ${totalTrips} trips for feed`}>
+              <Icon type='building-o' /> {totalTrips}
+            </BsLabel>
+          </>
+          : <>
+            <Icon type='warning' /> {this.messages('exceptionBasedCalendar')}
+          </>
+        }
       </span>
     )
   }
 
   _onChange = (value: CalendarOption) => {
     const {activePattern, feedSource, route, setActiveEntity} = this.props
-    const calendar = value && value.calendar
+    const calendar = value && (value.calendar || value)
     setActiveEntity(
       feedSource.id,
       'route',
@@ -94,9 +104,9 @@ export default class CalendarSelect extends Component<Props> {
   }
 
   _getOptions = (): Array<CalendarOption> => {
-    const {activePattern, calendars, tripCounts, trips} = this.props
+    const {activePattern, calendars, exceptionBasedCalendars, tripCounts, trips} = this.props
     const patternId = activePattern && activePattern.patternId
-    const calendarOptions: Array<CalendarOption> = calendars && activePattern
+    const calendarBasedOptions: Array<CalendarOption> = calendars && activePattern
       ? calendars
         .map(calendar => ({
           label: calendar.description || calendar.service_id,
@@ -111,6 +121,18 @@ export default class CalendarSelect extends Component<Props> {
         }))
       : []
 
+    // Add exception based calendars to the list
+    // TODO: trip counts (total v pattern)
+    const exceptionBasedCalendarOptions = exceptionBasedCalendars && exceptionBasedCalendars.map(exception => ({
+      label: exception.name || exception.id,
+      value: exception.service_id,
+      type: 'exception-based',
+      service_id: exception.service_id // For an exception based schedule the custom schedule should only have one entry.
+    }))
+
+    // $FlowFixMe: we need two types of options
+    const calendarOptions = calendarBasedOptions.concat(exceptionBasedCalendarOptions)
+
     return calendarOptions
       .sort((a, b) => {
         return b.patternTrips - a.patternTrips
@@ -128,7 +150,7 @@ export default class CalendarSelect extends Component<Props> {
     return (
       <Select
         value={activeCalendar && activeCalendar.service_id}
-        placeholder={<span><Icon type='calendar-o' /> Select calendar...</span>}
+        placeholder={<span><Icon type='calendar-o' />{this.messages('selectCalendar')}</span>}
         valueRenderer={this._optionRenderer}
         optionRenderer={this._optionRenderer}
         disabled={!activePattern || entityIsNew(activePattern)}
diff --git a/lib/editor/components/timetable/TimetableHeader.js b/lib/editor/components/timetable/TimetableHeader.js
index f688eca04..1b0ae34d7 100644
--- a/lib/editor/components/timetable/TimetableHeader.js
+++ b/lib/editor/components/timetable/TimetableHeader.js
@@ -22,9 +22,10 @@ import * as tripActions from '../../actions/trip'
 import OptionButton from '../../../common/components/OptionButton'
 import HourMinuteInput from '../HourMinuteInput'
 import {getTableById} from '../../util/gtfs'
-import { getComponentMessages } from '../../../common/util/config'
+import {getActiveCalendar, getExceptionBasedCalendars} from '../../util/timetable'
+import {getComponentMessages} from '../../../common/util/config'
 import type {TripValidationIssues} from '../../selectors/timetable'
-import type {Feed, GtfsRoute, Pattern, ServiceCalendar, TripCounts} from '../../../types'
+import type {Feed, GtfsRoute, Pattern, ServiceCalendar, ScheduleException, ScheduleExceptionCalendar, TripCounts} from '../../../types'
 import type {EditorTables, TimetableState} from '../../../types/reducers'
 
 import PatternSelect from './PatternSelect'
@@ -69,7 +70,9 @@ export default class TimetableHeader extends Component<Props> {
   _onClickUndoButton = (e: SyntheticInputEvent<HTMLInputElement>) => {
     const {activePattern, activeScheduleId, feedSource, fetchTripsForCalendar, tableData} = this.props
     const calendars: Array<ServiceCalendar> = getTableById(tableData, 'calendar')
-    const activeCalendar = calendars.find(c => c.service_id === activeScheduleId)
+    const scheduleExceptions: Array<ScheduleException> = getTableById(tableData, 'scheduleexception')
+    const exceptionBasedCalendars: Array<ScheduleExceptionCalendar> = getExceptionBasedCalendars(scheduleExceptions)
+    const activeCalendar = getActiveCalendar(calendars, exceptionBasedCalendars, activeScheduleId)
     if (activeCalendar) {
       fetchTripsForCalendar(feedSource.id, activePattern, activeCalendar.service_id)
     } else console.warn(`Could not locate calendar with service_id=${activeScheduleId}`)
@@ -117,7 +120,8 @@ export default class TimetableHeader extends Component<Props> {
     } = this.props
     const {edited, hideDepartureTimes, selected, trips, useSecondsInOffset} = timetable
     const calendars: Array<ServiceCalendar> = getTableById(tableData, 'calendar')
-    const activeCalendar = calendars.find(c => c.service_id === activeScheduleId)
+    const exceptionBasedCalendars = getExceptionBasedCalendars(getTableById(tableData, 'scheduleexception'))
+    const activeCalendar = getActiveCalendar(calendars, exceptionBasedCalendars, activeScheduleId)
     const headerStyle = {
       backgroundColor: 'white'
     }
@@ -370,14 +374,16 @@ export default class TimetableHeader extends Component<Props> {
           </Col>
           <Col xs={12} sm={3} data-test-id='calendar-select-container'>
             <CalendarSelect
-              activePattern={activePattern}
-              route={route}
-              feedSource={feedSource}
               activeCalendar={activeCalendar}
+              activePattern={activePattern}
               calendars={calendars}
+              exceptionBasedCalendars={exceptionBasedCalendars}
+              feedSource={feedSource}
+              route={route}
               setActiveEntity={setActiveEntity}
+              trips={trips}
               tripCounts={tripCounts}
-              trips={trips} />
+            />
           </Col>
           <Col sm={3}>
             {/* Edit timetable buttons */}
diff --git a/lib/editor/containers/ActiveTimetableEditor.js b/lib/editor/containers/ActiveTimetableEditor.js
index b70129bcc..3e5a86056 100644
--- a/lib/editor/containers/ActiveTimetableEditor.js
+++ b/lib/editor/containers/ActiveTimetableEditor.js
@@ -47,8 +47,7 @@ const mapStateToProps = (state: AppState, ownProps: Props) => {
   const columns = getTimetableColumns(state)
   const tripValidationErrors = getTripValidationErrors(state)
   const {subEntity: activePattern} = active
-  const activeSchedule = getTableById(tables, 'calendar')
-    .find(c => c.service_id === activeScheduleId)
+  const activeSchedule = getTableById(tables, 'calendar').find(c => c.service_id === activeScheduleId) || getTableById(tables, 'scheduleexception').find(ex => ex.custom_schedule && ex.custom_schedule[0] === activeScheduleId)
   const timetableStatus = state.editor.timetable.status
   return {
     activePatternId,
diff --git a/lib/editor/util/index.js b/lib/editor/util/index.js
index 4f9f4d29b..1670d9b66 100644
--- a/lib/editor/util/index.js
+++ b/lib/editor/util/index.js
@@ -30,7 +30,8 @@ export const EXCEPTION_EXEMPLARS = {
   SUNDAY: 6,
   NO_SERVICE: 7,
   CUSTOM: 8,
-  SWAP: 9
+  SWAP: 9,
+  EXCEPTION_SERVICE: 10
 }
 
 export const ROUTE_STATUS_CODES = {
diff --git a/lib/editor/util/timetable.js b/lib/editor/util/timetable.js
index 7fc1bd5d2..e184fc206 100644
--- a/lib/editor/util/timetable.js
+++ b/lib/editor/util/timetable.js
@@ -2,7 +2,9 @@
 
 import moment from 'moment'
 
-import type {TimetableColumn} from '../../types'
+import type {ScheduleException, ScheduleExceptionCalendar, ServiceCalendar, TimetableColumn} from '../../types'
+
+import { EXCEPTION_EXEMPLARS } from '.'
 
 /**
  * This object defines the timetable editor keyboard shorcuts.
@@ -48,6 +50,27 @@ export function parseTime (timeString: string) {
   )
 }
 
+// Helper function to find and return the active calendar, be it traditional or exception-based.
+export function getActiveCalendar (calendars: Array<ServiceCalendar>, exceptionBasedCalendars: Array<ScheduleExceptionCalendar>, activeScheduleId: string): ?ServiceCalendar | ?ScheduleExceptionCalendar {
+  const activeCalendarFilter = c => c.service_id === activeScheduleId
+  return calendars.find(activeCalendarFilter) || exceptionBasedCalendars.find(activeCalendarFilter)
+}
+
+// Function to filter schedule exceptions into exemplars for exception-based service and to modify the custom_schedule and
+// service_id in the format that the Timetable comoponents require.
+export function getExceptionBasedCalendars (scheduleExceptions: Array<ScheduleException>): Array<ScheduleExceptionCalendar> {
+  const exceptionBasedCalendars = scheduleExceptions && scheduleExceptions.reduce((calendars, exception) => {
+    if (exception.exemplar === EXCEPTION_EXEMPLARS.EXCEPTION_SERVICE) {
+      if (exception.custom_schedule && exception.custom_schedule[0]) {
+        calendars.push({...exception, custom_schedule: exception.custom_schedule[0], service_id: exception.custom_schedule[0]})
+      }
+    }
+    return calendars
+  }, [])
+  // $FlowFixMe: reduce confuses flow about custom_schedule type
+  return exceptionBasedCalendars
+}
+
 export const LEFT_COLUMN_WIDTH = 30
 export const ROW_HEIGHT = 25
 export const OVERSCAN_COLUMN_COUNT = 10
diff --git a/lib/editor/util/validation.js b/lib/editor/util/validation.js
index 806f1d111..a94e23b6a 100644
--- a/lib/editor/util/validation.js
+++ b/lib/editor/util/validation.js
@@ -4,12 +4,14 @@ import clone from 'lodash/cloneDeep'
 import moment from 'moment'
 import validator from 'validator'
 
-import type {Entity, GtfsSpecField, ScheduleException} from '../../types'
+import type {Entity, GtfsSpecField, ScheduleException, ServiceCalendar} from '../../types'
 import type {EditorTables} from '../../types/reducers'
 import { getComponentMessages } from '../../common/util/config'
 
 import {getTableById} from './gtfs'
 
+import { EXCEPTION_EXEMPLARS } from '.'
+
 export type EditorValidationIssue = {
   field: string,
   invalid: boolean,
@@ -332,6 +334,19 @@ export function validate (
         }
       }
 
+      // Special validation for exception based calendars
+      if (entity && entity.exemplar && entity.exemplar === EXCEPTION_EXEMPLARS.EXCEPTION_SERVICE) {
+        if (!entity.custom_schedule) valErrors.push(emptyFieldValidationIssue(messages('customServiceId')))
+        const calendars: Array<ServiceCalendar> = clone(getTableById(tableData, 'calendar'))
+
+        // Check if service ID exists elsewhere
+        // $FlowFixMe: Array#some confuses flow it seems.
+        if (entity.custom_schedule && calendars.some(c => c.service_id === entity.custom_schedule)) {
+          const reason = messages('conflictingServiceId')
+          valErrors.push(validationIssue(reason, messages('customServiceId')))
+        }
+      }
+
       for (let i = 0; i < scheduleExceptions.length; i++) {
         const scheduleException = scheduleExceptions[i]
         const serviceIds = getExceptionServiceIds(scheduleException)
diff --git a/lib/types/index.js b/lib/types/index.js
index 2942cbf29..82d7f134b 100644
--- a/lib/types/index.js
+++ b/lib/types/index.js
@@ -864,6 +864,20 @@ export type ScheduleException = {|
   removed_service: ?Array<string>
 |}
 
+export type ScheduleExceptionCalendar = {|
+  added_service: ?Array<string>,
+  custom_schedule: ?string, // An exception based calendar must have only one service_id in custom_schedule.
+  dates: Array<ExceptionDate>,
+  exemplar: number,
+  feedId: string,
+  id: number,
+  isCreating: boolean,
+  name: string,
+  removed_service: ?Array<string>,
+  service_id: string,
+
+|}
+
 export type ScheduleExceptionDateRange = {
   endDate: ExceptionDate,
   startDate: ExceptionDate
diff --git a/lib/types/reducers.js b/lib/types/reducers.js
index 2a72674f1..17a74223e 100644
--- a/lib/types/reducers.js
+++ b/lib/types/reducers.js
@@ -144,6 +144,7 @@ export type EditorTables = {
     tripPatterns?: Array<Pattern>
   }>,
   schedule_exceptions: Array<{
+    exemplar: number,
     id: number,
     name: string
   }>,