Achieving optimal upper limb function is a priority in the management of children with congenital hand malformations. Professionals need to be well equipped to help families understand the best surgical and rehabilitative options available for their child. Our ability as professionals clearly to define and evaluate the child's optimal function will assist in achieving this balance. This article examines the existing literature to evaluate critically functional outcome studies of children with congenital upper extremity malformations and to address the challenges of defining and measuring functional outcome in this patient population.