diff --git a/lib/Calendar.js b/lib/Calendar.js
index 6a062bbe9..b540dcb93 100644
--- a/lib/Calendar.js
+++ b/lib/Calendar.js
@@ -308,6 +308,8 @@ var Calendar = (function(_React$Component) {
       _0 = _props.components,
       _1 = _props.formats,
       _2 = _props.messages,
+      weekStart = _props.weekStart,
+      workWeekStart = _props.workWeekStart,
       props = _objectWithoutProperties(_props, [
         'view',
         'toolbar',
@@ -323,6 +325,8 @@ var Calendar = (function(_React$Component) {
         'components',
         'formats',
         'messages',
+        'weekStart',
+        'workWeekStart',
       ])
 
     current = current || getNow()
@@ -336,7 +340,12 @@ var Calendar = (function(_React$Component) {
       viewNames = _state$context.viewNames
 
     var CalToolbar = components.toolbar || _Toolbar2.default
-    var label = View.title(current, { localizer: localizer, length: length })
+    var label = View.title(current, {
+      localizer: localizer,
+      length: length,
+      weekStart: weekStart,
+      workWeekStart: workWeekStart,
+    })
 
     return _react2.default.createElement(
       'div',
@@ -372,6 +381,8 @@ var Calendar = (function(_React$Component) {
             getNow: getNow,
             length: length,
             localizer: localizer,
+            weekStart: weekStart,
+            workWeekStart: workWeekStart,
             getters: getters,
             components: components,
             accessors: accessors,
@@ -395,6 +406,12 @@ var Calendar = (function(_React$Component) {
 Calendar.propTypes = {
   localizer: _propTypes2.default.object.isRequired,
 
+  // When the week starts, 0 or 1.
+  weekStart: _propTypes2.default.number,
+
+  // When the work week starts, 0 or 1.
+  workWeekStart: _propTypes2.default.number,
+
   /**
    * Props passed to main calendar `<div>`.
    *
diff --git a/lib/Week.js b/lib/Week.js
index 3f8502b4a..079280d68 100644
--- a/lib/Week.js
+++ b/lib/Week.js
@@ -133,11 +133,10 @@ Week.navigate = function(date, action) {
 }
 
 Week.range = function(date, _ref) {
-  var localizer = _ref.localizer
+  var weekStart = _ref.weekStart
 
-  var firstOfWeek = localizer.startOfWeek()
-  var start = _dates2.default.startOf(date, 'week', firstOfWeek)
-  var end = _dates2.default.endOf(date, 'week', firstOfWeek)
+  var start = _dates2.default.startOf(date, 'week', weekStart)
+  var end = _dates2.default.endOf(date, 'week', weekStart)
 
   return _dates2.default.range(start, end)
 }
diff --git a/lib/WorkWeek.js b/lib/WorkWeek.js
index 31991d201..85dbaa500 100644
--- a/lib/WorkWeek.js
+++ b/lib/WorkWeek.js
@@ -24,6 +24,10 @@ var _react = require('react')
 
 var _react2 = _interopRequireDefault(_react)
 
+var _dates = require('./utils/dates')
+
+var _dates2 = _interopRequireDefault(_dates)
+
 var _Week = require('./Week')
 
 var _Week2 = _interopRequireDefault(_Week)
@@ -84,10 +88,13 @@ function _inherits(subClass, superClass) {
       : (subClass.__proto__ = superClass)
 }
 
-function workWeekRange(date, options) {
-  return _Week2.default.range(date, options).filter(function(d) {
-    return [6, 0].indexOf(d.getDay()) === -1
-  })
+function workWeekRange(date, _ref) {
+  var workWeekStart = _ref.workWeekStart
+
+  var start = _dates2.default.startOf(date, 'week', workWeekStart)
+  var end = _dates2.default.endOf(date, 'week', workWeekStart)
+
+  return _dates2.default.range(start, end).slice(0, 5)
 }
 
 var WorkWeek = (function(_React$Component) {
@@ -127,10 +134,11 @@ WorkWeek.range = workWeekRange
 
 WorkWeek.navigate = _Week2.default.navigate
 
-WorkWeek.title = function(date, _ref) {
-  var localizer = _ref.localizer
+WorkWeek.title = function(date, _ref2) {
+  var localizer = _ref2.localizer,
+    workWeekStart = _ref2.workWeekStart
 
-  var _workWeekRange = workWeekRange(date, { localizer: localizer }),
+  var _workWeekRange = workWeekRange(date, { workWeekStart: workWeekStart }),
     start = _workWeekRange[0],
     rest = _workWeekRange.slice(1)
 
diff --git a/src/Calendar.js b/src/Calendar.js
index dc843f0ca..d97724795 100644
--- a/src/Calendar.js
+++ b/src/Calendar.js
@@ -62,6 +62,12 @@ class Calendar extends React.Component {
   static propTypes = {
     localizer: PropTypes.object.isRequired,
 
+    // When the week starts, 0 or 1.
+    weekStart: PropTypes.number,
+
+    // When the work week starts, 0 or 1.
+    workWeekStart: PropTypes.number,
+
     /**
      * Props passed to main calendar `<div>`.
      *
@@ -833,6 +839,8 @@ class Calendar extends React.Component {
       components: _0,
       formats: _1,
       messages: _2,
+      weekStart,
+      workWeekStart,
       ...props
     } = this.props
 
@@ -848,7 +856,12 @@ class Calendar extends React.Component {
     } = this.state.context
 
     let CalToolbar = components.toolbar || Toolbar
-    const label = View.title(current, { localizer, length })
+    const label = View.title(current, {
+      localizer,
+      length,
+      weekStart,
+      workWeekStart,
+    })
 
     return (
       <div
@@ -876,6 +889,8 @@ class Calendar extends React.Component {
           getNow={getNow}
           length={length}
           localizer={localizer}
+          weekStart={weekStart}
+          workWeekStart={workWeekStart}
           getters={getters}
           components={components}
           accessors={accessors}
diff --git a/src/Week.js b/src/Week.js
index 7e8a1508d..b1dcd1762 100644
--- a/src/Week.js
+++ b/src/Week.js
@@ -32,10 +32,9 @@ Week.navigate = (date, action) => {
   }
 }
 
-Week.range = (date, { localizer }) => {
-  let firstOfWeek = localizer.startOfWeek()
-  let start = dates.startOf(date, 'week', firstOfWeek)
-  let end = dates.endOf(date, 'week', firstOfWeek)
+Week.range = (date, { weekStart }) => {
+  let start = dates.startOf(date, 'week', weekStart)
+  let end = dates.endOf(date, 'week', weekStart)
 
   return dates.range(start, end)
 }
diff --git a/src/WorkWeek.js b/src/WorkWeek.js
index 3db982dce..070a5aad4 100644
--- a/src/WorkWeek.js
+++ b/src/WorkWeek.js
@@ -1,13 +1,15 @@
 import PropTypes from 'prop-types'
 import React from 'react'
+import dates from './utils/dates'
 
 import Week from './Week'
 import TimeGrid from './TimeGrid'
 
-function workWeekRange(date, options) {
-  return Week.range(date, options).filter(
-    d => [6, 0].indexOf(d.getDay()) === -1
-  )
+function workWeekRange(date, { workWeekStart }) {
+  let start = dates.startOf(date, 'week', workWeekStart)
+  let end = dates.endOf(date, 'week', workWeekStart)
+
+  return dates.range(start, end).slice(0, 5)
 }
 
 class WorkWeek extends React.Component {
@@ -29,8 +31,8 @@ WorkWeek.range = workWeekRange
 
 WorkWeek.navigate = Week.navigate
 
-WorkWeek.title = (date, { localizer }) => {
-  let [start, ...rest] = workWeekRange(date, { localizer })
+WorkWeek.title = (date, { localizer, workWeekStart }) => {
+  let [start, ...rest] = workWeekRange(date, { workWeekStart })
 
   return localizer.format({ start, end: rest.pop() }, 'dayRangeHeaderFormat')
 }