Introduction Functional assessment of the hand with a validated scale can be used to evaluate rehabilitation interventions and optimize treatments that benefit children and youngsters with neuromusculoskeletal diseases. Objective To adapt and validate the Bilan 400 points scale, used in adult patients, to a population aged 7 to 17 years old with some degree of disability. Materials and methods The Bilan 400 points scale was translated from the original French to Spanish and vice-versa; face validity was obtained through consensus among 11 experts on the topic. Twenty-five occupational therapists were instructed in the management of the protocol and variability was controlled among the observers. Internal consistency was also evaluated. Construct validity was evaluated using main components analysis with varimax rotation in a random sample of 153 children and young people who met the inclusion criteria. Results There was strong agreement among the experts (80% to 100%) on the items of the protocol. The internal consistency varied between a Cronbach's α of 0.94 and 0.98 for the different dimensions, for the right and left hands. Three dimensions were identified: the first consisted of the sub-dimensions of mobility of the fingers, thumb, wrist and forearm; the second consisted of the sub-dimensions of precision grip, power grip and displacement of objects; and the third was the sub-dimension of manipulative skills of food utensils, clothing and school items. Conclusion The modified Bilan 400 points scale is a valid and reliable assessment tool that measures hand functionality in children and youngsters between 7 and 17 years of age with neuromusculoskeletal disability. © 2013 Elsevier España, S.L. y SERMEF. Todos los derechos reservados.