A controllable, multi-mode, bi-directional overrunning mode clutch and a shift system adapted for use in a power transfer assembly for transferring drive torque from a primary driveline to a secondary driveline so as to establish a four-wheel drive mode. The mode clutch includes a first ring journalled on a first rotary member, a second ring fixed to a second rotary member, and a plurality of rollers disposed in opposed cam tracks formed between the first and second rings. The first ring is split to define an actuation channel between its end segments. A cam member is moveable between positions engaged with and released from one or both end segments of the split first ring. The shift system includes a mode fork which controls movement of the cam member for establishing a two-wheel drive mode in addition to on-demand and locked four-wheel drive modes.