where options include:

 -new-instance      Open new instance, not a new window in running instance.

I think this is what you want; Usage: C:\PROGRA~1\MOZILL~1\firefox.exe [ options ... ] [URL] where options include: -new-instance Open new instance, not a new window in running instance.

You can add -no-remote to the command line to open another Firefox instance with its own profile and run multiple Firefox instances simultaneously. *http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile *https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles See also: *http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_windows *http://kb.mozillazine.org/Shortcut_to_a_specific_profile *http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox