Add the following entry to you projects module xml file. Add the following stylesheet to your host page. Ext GWT requires no doctype or the following doctype (quirksmode). Eclipse Setup (should be similiar for other development enviornments) These instructions assume you have a existing project and launch confifuration. 1. Add gxt.jar to the project. a. Right click on project name in 'Package Explorer'. b. Select 'Properties' from content menu. c. Select 'Java Build Path'. d. Select 'Libraries' tab. e. Add the gxt.jar either with 'Add JARs...' or 'Add External JARs...'. 2. Add GXT jar to launch configuration. a. Choose Run / Open Run Dialog. b. Select your appropriate launch configuration under 'Java Application'. c. Select the 'Classpath' tab. d. Add the gxt.jar to the classpath.