diff --git a/Cargo.lock b/Cargo.lock
index 6158dedff59..fef421abaf1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -659,6 +659,15 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b365fabc795046672053e29c954733ec3b05e4be654ab130fe8f1f94d7051f35"
 
+[[package]]
+name = "dark-light"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7120c3a2b4cbef379407b56cc808304a728cadc756605ab5f0b70619b4d44b9"
+dependencies = [
+ "winreg",
+]
+
 [[package]]
 name = "darling"
 version = "0.13.1"
@@ -806,6 +815,7 @@ name = "egui-winit"
 version = "0.16.0"
 dependencies = [
  "copypasta",
+ "dark-light",
  "egui",
  "epi",
  "instant",
@@ -3018,6 +3028,15 @@ dependencies = [
  "x11-dl",
 ]
 
+[[package]]
+name = "winreg"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d107f8c6e916235c4c01cabb3e8acf7bea8ef6a63ca2e7fa0527c049badfc48c"
+dependencies = [
+ "winapi",
+]
+
 [[package]]
 name = "x11-clipboard"
 version = "0.5.3"
diff --git a/eframe/CHANGELOG.md b/eframe/CHANGELOG.md
index 42e78ccad3b..ebe4c607f75 100644
--- a/eframe/CHANGELOG.md
+++ b/eframe/CHANGELOG.md
@@ -8,6 +8,7 @@ NOTE: [`egui_web`](../egui_web/CHANGELOG.md), [`egui-winit`](../egui-winit/CHANG
 * Removed `Frame::alloc_texture`. Use `egui::Context::load_texture` instead ([#1110](https://github.com/emilk/egui/pull/1110)).
 * The default native backend is now `egui_glow` (instead of `egui_glium`) ([#1020](https://github.com/emilk/egui/pull/1020)).
 * The default web painter is now `egui_glow` (instead of WebGL) ([#1020](https://github.com/emilk/egui/pull/1020)).
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
 * Fix horizontal scrolling direction on Linux.
 * Added `App::on_exit_event` ([#1038](https://github.com/emilk/egui/pull/1038))
 * Shift-scroll will now result in horizontal scrolling on all platforms ([#1136](https://github.com/emilk/egui/pull/1136)).
diff --git a/egui-winit/CHANGELOG.md b/egui-winit/CHANGELOG.md
index 426fbc6a206..80de1eaa77b 100644
--- a/egui-winit/CHANGELOG.md
+++ b/egui-winit/CHANGELOG.md
@@ -5,6 +5,7 @@ All notable changes to the `egui-winit` integration will be noted in this file.
 
 ## Unreleased
 * Fixed horizontal scrolling direction on Linux.
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
 * Replaced `std::time::Instant` with `instant::Instant` for WebAssembly compatability ([#1023](https://github.com/emilk/egui/pull/1023))
 * Shift-scroll will now result in horizontal scrolling on all platforms ([#1136](https://github.com/emilk/egui/pull/1136)).
 * Require knowledge about max texture side (e.g. `GL_MAX_TEXTURE_SIZE`)) ([#1154](https://github.com/emilk/egui/pull/1154)).
diff --git a/egui-winit/Cargo.toml b/egui-winit/Cargo.toml
index 8e6c88824ac..6140ab66183 100644
--- a/egui-winit/Cargo.toml
+++ b/egui-winit/Cargo.toml
@@ -30,6 +30,7 @@ winit = "0.26.1"
 epi = { version = "0.16.0", path = "../epi", optional = true }
 
 copypasta = { version = "0.7", optional = true }
+dark-light = { version = "0.1.1", optional = true } # detect dark mode system preference
 serde = { version = "1.0", optional = true, features = ["derive"] }
 webbrowser = { version = "0.5", optional = true }
 
@@ -37,7 +38,7 @@ webbrowser = { version = "0.5", optional = true }
 tts = { version = "0.19", optional = true }
 
 [features]
-default = ["clipboard", "links"]
+default = ["clipboard", "dark-light", "links"]
 
 # enable cut/copy/paste to OS clipboard.
 # if disabled a clipboard will be simulated so you can still copy/paste within the egui app.
diff --git a/egui-winit/src/epi.rs b/egui-winit/src/epi.rs
index 995d8f8b4ff..b4762be5d6a 100644
--- a/egui-winit/src/epi.rs
+++ b/egui-winit/src/epi.rs
@@ -223,11 +223,13 @@ impl EpiIntegration {
 
         *egui_ctx.memory() = persistence.load_memory().unwrap_or_default();
 
+        let prefer_dark_mode = prefer_dark_mode();
+
         let frame = epi::Frame::new(epi::backend::FrameData {
             info: epi::IntegrationInfo {
                 name: integration_name,
                 web_info: None,
-                prefer_dark_mode: None, // TODO: figure out system default
+                prefer_dark_mode,
                 cpu_usage: None,
                 native_pixels_per_point: Some(crate::native_pixels_per_point(window)),
             },
@@ -235,6 +237,12 @@ impl EpiIntegration {
             repaint_signal,
         });
 
+        if prefer_dark_mode == Some(true) {
+            egui_ctx.set_visuals(egui::Visuals::dark());
+        } else {
+            egui_ctx.set_visuals(egui::Visuals::light());
+        }
+
         let mut slf = Self {
             frame,
             persistence,
@@ -340,3 +348,16 @@ impl EpiIntegration {
             .save(&mut *self.app, &self.egui_ctx, window);
     }
 }
+
+#[cfg(feature = "dark-light")]
+fn prefer_dark_mode() -> Option<bool> {
+    match dark_light::detect() {
+        dark_light::Mode::Dark => Some(true),
+        dark_light::Mode::Light => Some(false),
+    }
+}
+
+#[cfg(not(feature = "dark-light"))]
+fn prefer_dark_mode() -> Option<bool> {
+    None
+}
diff --git a/egui_glium/CHANGELOG.md b/egui_glium/CHANGELOG.md
index 45cb11391dd..3de396f5412 100644
--- a/egui_glium/CHANGELOG.md
+++ b/egui_glium/CHANGELOG.md
@@ -5,6 +5,7 @@ All notable changes to the `egui_glium` integration will be noted in this file.
 ## Unreleased
 * `EguiGlium::run` no longer returns the shapes to paint, but stores them internally until you call `EguiGlium::paint` ([#1110](https://github.com/emilk/egui/pull/1110)).
 * Optimize the painter and texture uploading ([#1110](https://github.com/emilk/egui/pull/1110)).
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
 
 
 ## 0.16.0 - 2021-12-29
diff --git a/egui_glow/CHANGELOG.md b/egui_glow/CHANGELOG.md
index a5eaa4b2182..b5bcdb6de09 100644
--- a/egui_glow/CHANGELOG.md
+++ b/egui_glow/CHANGELOG.md
@@ -7,7 +7,9 @@ All notable changes to the `egui_glow` integration will be noted in this file.
 * Added `set_texture_filter` method to `Painter` ([#1041](https://github.com/emilk/egui/pull/1041)).
 * Fix failure to run in Chrome ([#1092](https://github.com/emilk/egui/pull/1092)).
 * `EguiGlow::new` now takes `&winit::Window` because there are no reason to use `&glutin::WindowedContext` ([#1151](https://github.com/emilk/egui/pull/1151)).
-* `EguiGlow::paint` now takes `&winit::Window` because there are no reason to use `&glutin::WindowedContext` ([#1151](https://github.com/emilk/egui/pull/1151)).  
+* `EguiGlow::paint` now takes `&winit::Window` because there are no reason to use `&glutin::WindowedContext` ([#1151](https://github.com/emilk/egui/pull/1151)).
+* Automatically detect and apply dark or light mode from system ([#1045](https://github.com/emilk/egui/pull/1045)).
+
 
 ## 0.16.0 - 2021-12-29
 * Made winit/glutin an optional dependency ([#868](https://github.com/emilk/egui/pull/868)).
diff --git a/egui_glow/Cargo.toml b/egui_glow/Cargo.toml
index 9b307f1c55f..cd0add6e00e 100644
--- a/egui_glow/Cargo.toml
+++ b/egui_glow/Cargo.toml
@@ -35,7 +35,7 @@ memoffset = "0.6"
 tracing = "0.1"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-egui-winit = { version = "0.16.0", path = "../egui-winit", default-features = false, features = ["epi"], optional = true }
+egui-winit = { version = "0.16.0", path = "../egui-winit", default-features = false, features = ["dark-light", "epi"], optional = true }
 glutin = { version = "0.28.0", optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]