This monograph discusses the evolution of Marine Corps mechanized forces and their role in future conflicts. In a crisis, joint force commanders will likely request early insertion of a mechanized Marine Expeditionary Brigade, using assets forward deployed aboard a Maritime Prepositioning Force squadron, because the MEB promotes the rapid build up of combat power even in an austere environment. Joint planners should understand that an MPS resourced MEB, with equipment and force structure designed for amphibious operations, cannot be employed in the same manner as an Army mechanized brigade. The monograph first examines whether the Marine Corps needs mechanized forces to fulfill assigned roles and missions. Since the National Security Act codified the Marine Corps' role as the nation's principle amphibious rapid response force, the evolving threat has forced the service to gradually increase its mechanized capabilities, largely through equipment modernization. The MPS resourced MEB is the end result of efforts to maintain a rapid insertion, amphibious-capable force that can deter opposing mechanized forces until heavier forces arrive. Next, the monograph contrasts the MEB with an Army balanced heavy brigade. The MEB is a partially mechanized infantry force that relies on air power to make up for a shortfall in ground antiarmor weapons systems. These characteristics limit the flexibility of the MEB in offensive operations and complicate operational planning. Limited armored antiarmor systems hinder the execution of maneuver dependant operations, specifically the envelopment and the penetration. On the other hand, the MEB is well suited for defensive operations and for any operations in restrictive terrain. The monograph concludes by analyzing how the Advanced Amphibious Assault Vehicle (AAAV) will improve mechanized operations in the Marine Corps.