diff --git a/src/Calculator/App.xaml.cpp b/src/Calculator/App.xaml.cpp
index 2936680d..928a5d81 100644
--- a/src/Calculator/App.xaml.cpp
+++ b/src/Calculator/App.xaml.cpp
@@ -70,6 +70,20 @@ App::App()
     this->HighContrastAdjustment = ApplicationHighContrastAdjustment::None;
 
     this->Suspending += ref new SuspendingEventHandler(this, &App::OnSuspending);
+    auto value = Windows::Storage::ApplicationData::Current->LocalSettings->Values->Lookup(L"themeSetting");
+    if (value != nullptr)
+    {
+        String ^ colorS = safe_cast<String ^>(value);
+        // Apply theme choice.
+        if (colorS == L"Dark")
+        {
+            App::Current->RequestedTheme = ApplicationTheme::Dark;
+        }
+        else if (colorS == L"Light")
+        {
+            App::Current->RequestedTheme = ApplicationTheme::Light;
+        }
+    }
 
 #if _DEBUG
     this->DebugSettings->IsBindingTracingEnabled = true;
diff --git a/src/Calculator/Resources/en-US/Resources.resw b/src/Calculator/Resources/en-US/Resources.resw
index 850db11b..e5a2a3ab 100644
--- a/src/Calculator/Resources/en-US/Resources.resw
+++ b/src/Calculator/Resources/en-US/Resources.resw
@@ -4770,4 +4770,8 @@
     <value>Microsoft Privacy Statment</value>
     <comment>Displayed on a link to the Microsoft Privacy Statement on the Settings page.</comment>
   </data>
+  <data name="SettingsRestartNotice" xml:space="preserve">
+    <value>You'll see your changes the next time you start the app.</value>
+    <comment>Notice when the user change the theme.</comment>
+  </data>
 </root>
\ No newline at end of file
diff --git a/src/Calculator/SettingsPage.xaml b/src/Calculator/SettingsPage.xaml
index 07b3145d..ce82694f 100644
--- a/src/Calculator/SettingsPage.xaml
+++ b/src/Calculator/SettingsPage.xaml
@@ -17,7 +17,7 @@
                            MinHeight="{StaticResource HamburgerHeight}"
                            MaxHeight="52"/>
             <RowDefinition Height="4*"/>
-            <RowDefinition Height="1*" MaxHeight="32"/>
+            <RowDefinition Height="Auto" MinHeight="32"/>
             <RowDefinition Height="4*"/>
         </Grid.RowDefinitions>
 
@@ -32,17 +32,22 @@
                        AutomationProperties.HeadingLevel="Level1"
                        TextTrimming="Clip"/>
 
+            <TextBlock x:Name="SettingsRestartApp" Style="{StaticResource BodyTextBlockStyle}"/>
+
             <RadioButton x:Name="SettingsLightTheme"
                          x:Uid="SettingsLightTheme"
-                         Grid.Row="2"/>
+                         Grid.Row="2"
+                         Checked="LightChecked"/>
 
             <RadioButton x:Name="SettingsDarkTheme"
                          x:Uid="SettingsDarkTheme"
-                         Grid.Row="3"/>
+                         Grid.Row="3"
+                         Checked="DarkChecked"/>
 
             <RadioButton x:Name="SettingsSystemTheme"
                          x:Uid="SettingsSystemTheme"
-                         Grid.Row="4"/>
+                         Grid.Row="4"
+                         Checked="SystemChecked"/>
 
             <HyperlinkButton x:Name="ColorSettingsButton"
                              Margin="0,-2"
diff --git a/src/Calculator/SettingsPage.xaml.cpp b/src/Calculator/SettingsPage.xaml.cpp
index fb4e554a..679a2b85 100644
--- a/src/Calculator/SettingsPage.xaml.cpp
+++ b/src/Calculator/SettingsPage.xaml.cpp
@@ -32,10 +32,31 @@ SettingsPage::SettingsPage()
 
 	InitializeComponent();
 
+    SettingsRestartApp->Visibility = Windows::UI::Xaml::Visibility::Collapsed;
+
     Language = locService->GetLanguage();
 
     this->SetVersionString();
     this->SetCopyrightString();
+
+    auto value = Windows::Storage::ApplicationData::Current->LocalSettings->Values->Lookup(L"themeSetting");
+    if (value != nullptr)
+    {
+        String ^ colorS = safe_cast<String ^>(value);
+        // Apply theme choice.
+        if (colorS == L"Dark")
+        {
+            SettingsDarkTheme->IsChecked = true;
+        }
+        else if (Windows::Storage::ApplicationData::Current->LocalSettings->Values->Lookup(L"isSytemTheme"))
+        {
+            SettingsSystemTheme->IsChecked = true;
+        }
+        else if (colorS == L"Light")
+        {
+            SettingsLightTheme->IsChecked = true;
+        }
+    }
 }
 
 void SettingsPage::SetVersionString()
@@ -67,3 +88,41 @@ void SettingsPage::SettingsFeedbackButtonClick(_In_ Object ^ sender, _In_ Routed
 
     Launcher::LaunchUriAsync(ref new Uri("windows-feedback:?contextid=130&metadata=%7B%22Metadata%22:[%7B%22AppBuild%22:%22" + versionNumber + "%22%7D]%7D"));
 }
+
+void SettingsPage::LightChecked(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e)
+{
+    auto resourceLoader = AppResourceProvider::GetInstance();
+
+    SettingsRestartApp->Visibility = Windows::UI::Xaml::Visibility::Visible;
+    SettingsRestartApp->Text = LocalizationStringUtil::GetLocalizedString(resourceLoader->GetResourceString("SettingsRestartNotice"));
+    Windows::Storage::ApplicationData::Current->LocalSettings->Values->Insert(L"themeSetting", ApplicationTheme::Light.ToString());
+}
+
+void SettingsPage::DarkChecked(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e)
+{
+    auto resourceLoader = AppResourceProvider::GetInstance();
+
+    SettingsRestartApp->Visibility = Windows::UI::Xaml::Visibility::Visible;
+    SettingsRestartApp->Text = LocalizationStringUtil::GetLocalizedString(resourceLoader->GetResourceString("SettingsRestartNotice"));
+    Windows::Storage::ApplicationData::Current->LocalSettings->Values->Insert(L"themeSetting", ApplicationTheme::Dark.ToString());
+}
+
+void SettingsPage::SystemChecked(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e)
+{
+    auto resourceLoader = AppResourceProvider::GetInstance();
+    auto DefaultTheme = ref new Windows::UI::ViewManagement::UISettings();
+    auto uiTheme = DefaultTheme->GetColorValue(Windows::UI::ViewManagement::UIColorType::Background).ToString();
+
+    SettingsRestartApp->Visibility = Windows::UI::Xaml::Visibility::Visible;
+    SettingsRestartApp->Text = LocalizationStringUtil::GetLocalizedString(resourceLoader->GetResourceString("SettingsRestartNotice"));
+    Windows::Storage::ApplicationData::Current->LocalSettings->Values->Insert(L"isSytemTheme", true);
+
+    if (uiTheme == Windows::UI::Colors::Black.ToString())
+    {
+        Windows::Storage::ApplicationData::Current->LocalSettings->Values->Insert(L"themeSetting", ApplicationTheme::Dark.ToString());
+    }
+    else if (uiTheme == Windows::UI::Colors::White.ToString())
+    {
+        Windows::Storage::ApplicationData::Current->LocalSettings->Values->Insert(L"themeSetting", ApplicationTheme::Light.ToString());
+    }
+}
diff --git a/src/Calculator/SettingsPage.xaml.h b/src/Calculator/SettingsPage.xaml.h
index 14e9a73b..b72952c4 100644
--- a/src/Calculator/SettingsPage.xaml.h
+++ b/src/Calculator/SettingsPage.xaml.h
@@ -18,5 +18,8 @@ namespace CalculatorApp
         void SettingsFeedbackButtonClick(_In_ Platform::Object ^ sender, _In_ Windows::UI::Xaml::RoutedEventArgs ^ e);
         void SetVersionString();
         void SetCopyrightString();
+        void LightChecked(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e);
+        void DarkChecked(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e);
+        void SystemChecked(Platform::Object ^ sender, Windows::UI::Xaml::RoutedEventArgs ^ e);
     };
 }