The Whole Gang's Here

 is a trophy in Fallout: New Vegas which is awarded for successfully convincing all of the companions to join you.

Bugs

 * This trophy is apparently bugged and instead of hiring all of the companions, all you need to do is hire/rehire any companion as many times as there are companions. (May not work on all systems)
 * On the xbox 360, the acheivment will usually glitch, to where you will not unlock it after you find them all, the easeiest way to attempt to fix this is to have them all go to the same place (Lucky 38 suite is reccomended) abd just constantly asking them to follow you, than return to Lucky 38.
 * Instead of hiring all companions, it may unlock simply by meeting all them and not hiring any.