A dolly assembly including a plurality of hollow interior guide members and one or more rail members, cooperatively structured, configured and dimensioned to be selectively disposed in an operative, weight supporting orientation or a self-contained orientation of reduced dimension and configuration, which facilitates storage. The operative orientation comprises the one or more rail member removably interconnecting the two guide members in spaced relation to one another, wherein a plurality of castors are removably connected to and disposed in movable supporting relation with the interconnected guide and rail members, when in the operative orientation. The self-contained orientation comprises the guide members detached from the operative orientation and the guide members removably connected in confronting, predetermined facing relation to one another, such that the rail members and castors are enclosed within one or both of the hollow interiors of the confronting guide members.