Anabolic-androgenic steroids (AAS) are necessary for normal male sexual differentiation and development and pubertal development. Androgen therapy is appropriate for boys with delayed development (constitutional delay of growth and puberty, CDGP) as well as those with primary or secondary hypogonadism. The principal goal is to restore the serum testosterone (T) level to the normal range at each stage of adolescent development and then to the normal adult range if the hypogonadism is permanent. In addition the levels of dihydrotestosterone and estradiol should also be within the normal range. One should be able to do that with a wide variety of androgen preparations-injectable, implantable, and cutaneous patches or gels. However, during the transition from prepubertal to adult it is difficult to reliably deliver the relatively small doses of T necessary for adolescent development using any of the cutaneous preparations. Androgen therapy should permit normal linear growth (including the adolescent growth spurt), adolescent sexual development, and the attainment of normal body composition including lean body mass, bone and the appropriate regional distribution of body fat as well as the psychological development appropriate for the stage of adolescent development.