We are a medium sized business using Firefox 27.0.1. I have been looking for a way to control private browsing via group policy for a while but there are no clear answers on how a system administrator can do this without a convoluted process of editing files that can't be found anywhere on a computer. Our environment: windows 2008 DC using group policy 500 users, all windows Do not use any proxy or L7 filtering I've looked into using the adm file that is available from the link below. I've sifted through the code and followed instructions for the lockdown process for Computer and User configuration; however, nothing works. http://4sysops.com/archives/group-policy-for-firefox-and-chrome/#download-the-adm-files If someone can point me to a registry entry or a vbs file that can be used as a start up script, it would be greatly appreciated by myself and all the system administrators of the world that are trying to decrease private browsing in organizations. Between the 3 major browsers we are using on our Windows platform (IE, Chrome Firefox); Firefox seems to be a challenge to control. I have been successful in controlling settings via group policy for the other two. I'm working on a cumulative step by step document for this and will share with the world when I am able to configure Firefox.