Class II division I malocclusion is a very common orthodontic problem which is mostly accompanied with mandibular skeletal retrusion in children. Functional appliance aims at increasing the potential of growth and helps to guide the developing face and dentition towards a path of optimal development.Twin Block is the most accepted and widely used functional appliance for the correction of mandibular skeletal retrusion. It increases growth of the condylar cartilage thus helping in repositioning the mandible forwards. An early treatment of this malocclusion provides improvement in the self-esteem of the treated group.