Class II malocclusion may present with skeletal features of mandibular retrognathism, midface protrusion, and dental features of distal step molar relation, an unusually large overjet, and/or a variable combination of these features. With a variety of craniofacial morphology associated with Class II malocclusion, the type of functional appliance (FA) to choose and the timings of treatment are fundamental to treatment outcome and prognosis. Mandibular retrognathism has befallen to be the most universal rationale for availing orthodontic treatment. Europeans have traditionally tried to grow locked mandible in young children efficiently by jaw propulsors, collectively termed as FAs. FAs have come a long way since the introduction of the “bite-jumping” appliances by Norman Kingsley with the gradual evolution of these appliances through monobloc, activator, Frankel, bionator, twin block appliance, and fixed functional appliances which can now be attached to facial skeleton with implant anchorage.