diff --git a/CHANGELOG.md b/CHANGELOG.md
index 005bfa2a..d9b91006 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Commands to toggle mission-control, show-desktop, and application expose [#147](https://github.com/koekeishiya/yabai/issues/147)
 - Command to close windows that provide a close button in its titlebar [#84](https://github.com/koekeishiya/yabai/issues/84)
 - Expose window shadow as a property in window queries and add shadow as an option to *window --toggle* [#171](https://github.com/koekeishiya/yabai/issues/171)
+- Config option to set the duration of the transition between active / normal window opacity [#208](https://github.com/koekeishiya/yabai/issues/208)
 
 ### Changed
 - Automatically restart Dock.app after installing the scripting-addition, and tweak messages shown when a payload gets loaded, is already loaded or does not support the version of macOS it's running on [#135](https://github.com/koekeishiya/yabai/issues/135)
diff --git a/doc/yabai.1 b/doc/yabai.1
index 3e3364e8..ee34e654 100644
--- a/doc/yabai.1
+++ b/doc/yabai.1
@@ -60,12 +60,12 @@ Use the specified configuration file.
 .sp
 \fB\-\-install\-sa\fP
 .RS 4
-Install scripting\-addition. Must be ran as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
+Install scripting\-addition. Must be run as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
 .RE
 .sp
 \fB\-\-uninstall\-sa\fP
 .RS 4
-Uninstall scripting\-addition. Must be ran as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
+Uninstall scripting\-addition. Must be run as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
 .RE
 .sp
 \fB\-\-check\-sa\fP
@@ -186,6 +186,11 @@ Make floating windows stay on top.
 Enable opacity for windows.
 .RE
 .sp
+\fIwindow_opacity_duration\fP
+.RS 4
+Duration of transition between active / normal opacity.
+.RE
+.sp
 \fIwindow_shadow\fP
 .RS 4
 Draw shadow for windows. Accept the following values: \fBon\fP, \fBfloat\fP, \fBoff\fP.
diff --git a/doc/yabai.asciidoc b/doc/yabai.asciidoc
index ba828b1c..f53dcfff 100644
--- a/doc/yabai.asciidoc
+++ b/doc/yabai.asciidoc
@@ -46,10 +46,10 @@ Options
     Use the specified configuration file.
 
 *--install-sa*::
-    Install scripting-addition. Must be ran as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
+    Install scripting-addition. Must be run as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
 
 *--uninstall-sa*::
-    Uninstall scripting-addition. Must be ran as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
+    Uninstall scripting-addition. Must be run as root. Path is /System/Library/ScriptingAdditions on macOS High Sierra, and /Library/ScriptingAdditions on Mojave and newer.
 
 *--check-sa*::
     Returns a zero exit-code if the latest version of the scripting-addition is installed.
@@ -141,6 +141,9 @@ Colors are in the form '#AARRGGBB'.
 'window_opacity'::
     Enable opacity for windows.
 
+'window_opacity_duration'::
+    Duration of transition between active / normal opacity.
+
 'window_shadow'::
     Draw shadow for windows. Accept the following values: *on*, *float*, *off*.
 
diff --git a/examples/yabairc b/examples/yabairc
index a0ffeea2..795c85e6 100755
--- a/examples/yabairc
+++ b/examples/yabairc
@@ -17,6 +17,7 @@ yabai -m config focus_follows_mouse          off
 yabai -m config window_placement             second_child
 yabai -m config window_topmost               off
 yabai -m config window_opacity               off
+yabai -m config window_opacity_duration      0.0
 yabai -m config window_shadow                on
 yabai -m config window_border                off
 yabai -m config window_border_width          4
diff --git a/src/message.c b/src/message.c
index 05a7caa6..630aaa1b 100644
--- a/src/message.c
+++ b/src/message.c
@@ -22,6 +22,7 @@ extern struct bar g_bar;
 #define COMMAND_CONFIG_WINDOW_PLACEMENT      "window_placement"
 #define COMMAND_CONFIG_TOPMOST               "window_topmost"
 #define COMMAND_CONFIG_OPACITY               "window_opacity"
+#define COMMAND_CONFIG_OPACITY_DURATION      "window_opacity_duration"
 #define COMMAND_CONFIG_SHADOW                "window_shadow"
 #define COMMAND_CONFIG_BORDER                "window_border"
 #define COMMAND_CONFIG_BORDER_WIDTH          "window_border_width"
@@ -367,6 +368,13 @@ static void handle_domain_config(FILE *rsp, struct token domain, char *message)
         } else {
             daemon_fail(rsp, "unknown value '%.*s' given to command '%.*s' for domain '%.*s'\n", value.length, value.text, command.length, command.text, domain.length, domain.text);
         }
+    } else if (token_equals(command, COMMAND_CONFIG_OPACITY)) {
+        struct token value = get_token(&message);
+        if (!token_is_valid(value)) {
+            fprintf(rsp, "%f\n", g_window_manager.window_opacity_duration);
+        } else {
+            g_window_manager.window_opacity_duration = token_to_float(value);
+        }
     } else if (token_equals(command, COMMAND_CONFIG_SHADOW)) {
         struct token value = get_token(&message);
         if (!token_is_valid(value)) {
diff --git a/src/window_manager.c b/src/window_manager.c
index 47408be9..11d57f04 100644
--- a/src/window_manager.c
+++ b/src/window_manager.c
@@ -423,7 +423,7 @@ void window_manager_set_window_opacity(struct window_manager *wm, struct window
     char message[MAXLEN];
 
     if (socket_connect_un(&sockfd, g_sa_socket_file)) {
-        snprintf(message, sizeof(message), "window_alpha_fade %d %f %f", window->id, opacity, 0.2f);
+        snprintf(message, sizeof(message), "window_alpha_fade %d %f %f", window->id, opacity, wm->window_opacity_duration);
         socket_write(sockfd, message);
         socket_wait(sockfd);
     }
@@ -1501,6 +1501,7 @@ void window_manager_init(struct window_manager *wm)
     wm->insert_window_border_color = 0xfff57f7f;
     wm->active_window_opacity = 1.0f;
     wm->normal_window_opacity = 1.0f;
+    wm->window_opacity_duration = 0.2f;
 
     table_init(&wm->application, 150, hash_wm, compare_wm);
     table_init(&wm->window, 150, hash_wm, compare_wm);
diff --git a/src/window_manager.h b/src/window_manager.h
index e467ca1b..0b2106dd 100644
--- a/src/window_manager.h
+++ b/src/window_manager.h
@@ -71,6 +71,7 @@ struct window_manager
     uint32_t insert_window_border_color;
     float active_window_opacity;
     float normal_window_opacity;
+    float window_opacity_duration;
 };
 
 void window_manager_query_windows_for_space(FILE *rsp, uint64_t sid);