Abstract: A deactivating roller follower assembly for deactivating an associated poppet valve for an internal combustion engine includes a body including a valve end, a pivot end, and a plunger bore. The valve end of the body is configured to contact the associated poppet valve and the pivot end of the body is configured to contact a pivot of the associated internal combustion engine. The assembly further includes a pivotable arm including a hinged end and a free end. The hinged end is rotatably mounted to the valve end of the body. The free end includes a curvilinear engaging surface for transmitting a force required to activate the associated poppet valve. In addition, the assembly includes a plunger including a latching end and a piston end. The plunger is disposed in the plunger bore in the pivot end of the body. The plunger moves between an extended position and a retracted position.