Adults who give proxy consent for medical treatment for adolescents must decide how much weight to give to adolescents' own preferences. There is evidence that some adolescents choose treatments different from what adults see as most reasonable. It is argued that adolescents choose according to age-specific values, i.e. values they hold, as adolescents, and which fulfil important developmental needs. Because not fulfilling these needs may do serious psychological damage, it is urged that proxies give weight to these values, up to the limit where it would endanger or profoundly limit future life.