Abstract: The invention provides a two-step rocker arm assembly for use in an internal combustion engine in which a plurality of two-step rocker arm assemblies enable the engine poppet valves to switch between two lift profiles. The two-step rocker arm assembly of the present invention has an inner rocker arm assembly and an outer rocker arm assembly. The outer rocker arm assembly is characterized as having two rail portions spaced from each other forming an open space within which at least a portion of the inner rocker arm is disposed. Each of the rail portions and the inner rocker arm assembly has a generally cylindrical roller cam follower rotatably affixed thereto. Preferably, each of the roller element cam followers will be shaft mounted, the shafts being welded to the respective inner rocker arm and outer rocker arm for increased structural rigidity.