Installing multiple versions on Mac OS X is basically dragging the Firefox application out of the DMG file to the desktop and rename the folder. You can drag the renamed Firefox application folder to the Applications folder like you would normally install Firefox. *https://support.mozilla.org/kb//Installing+Firefox+on+Mac Firefox 45.6.0 ESR: *https://www.mozilla.org/en-US/firefox/organizations/all/ *https://www.mozilla.org/en-US/firefox/organizations/notes/ *https://www.mozilla.org/en-US/firefox/organizations/system-requirements/ You can add -no-remote to the command line to open another Firefox instance with its own profile and run multiple Firefox instances simultaneously each with their own profile. *https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles *https://developer.mozilla.org/Command_Line_Options

I managed to borrow a friends mac. I have installed both versions of Firefox by selecting keep both but only one version appears in the Launchpad. How do I add both? One is called Firefox the other is called Firefox 2. But only Firefox appears in the Launchpad.