Google Toolbar doesn't support newer versions of Firefox because Google decided that its functionality was mostly built into Firefox itself now or otherwise available via a Firefox addon: * http://googletoolbarhelp.blogspot.com/2011/07/update-on-google-toolbar-for-firefox.html Google provides the following help article on the topic: * http://www.google.com/support/toolbar/bin/answer.py?answer=1342452&topic=15356 Note that Firefox 4 is not supported by Mozilla anymore. To get the required security and stability updates, users need to install the later Firefox updates (currently Firefox 7..0.1).