Yes it works, but on OSX there's a potential Java hitch to be aware of. Download "Eclipse Ganymede 3.4":http://www.eclipse.org/downloads/. Unzip Eclipse to a directory (normally Applications). Download "Flex Builder 3.01 Plugin":https://www.adobe.com/cfusion/tdrc/index.cfm?loc=en_us&product=flex_eclipse. *BEFORE* you run the Flex Builder Plugin installer on OSX, check that your java version is set to 1.5. However a simple @java -version@ is not enough to satisfy the installer. You also have to @cd /System/Library/Frameworks/JavaVM.framework/Versions/@ and @ls -al@ to check that CurrentJDK -> 1.5.0. I'd previously installed Java 1.6 on Mac, and although @java -version@ gave me 1.5, the CurrentJDK -> 1.6.0. This seems to have caused my install to fail with the error: 'This installation can still be configured manually as a Product Extension' and soon after an alert with 'a newer file named "com.adobe.flexbuilder.debug.e33_3.0.205647.jar" already exists at "/Applications/Adobe Flex Builder 3 Plug-in/eclipse/plugins" Do you want to overwrite this file?' Trying to follow the instructions offered is a fruitless exercise I won't bother recounting because "someone else already has":http://www.newviewnetworks.com/nvnhome/blog/client/?p=103 (Borg - no permalinks for comments on that site). Anyway ensuring you have 1.5.0 all the way should guarantee a successful install. 2008-11-18T16:45:27Z 0 25 flex-builder-3-01-plugin-in-eclipse-ganymede-3-4-on-osx 2008-11-18T17:06:09Z