This invention relates of a support assembly (10) for a vehicle (16) of the type that includes an enclosed load carrying compartment (17) having a roof (18), said support assembly being adapted to provide support for a person when moving about on said roof. The support assembly includes a guide (11) that is mountable on the roof and a base (12) that is adapted to engage said guide and which is capable of movement along said guide while remaining engaged therewith. The support assembly also includes a support structure that includes a lower end portion that is pivotally connected to the base and a handle (15) that is spaced from said base. The support assembly also includes a lock (73) for selectively locking the support structure in a desired attitude relative to the base.