Puberty is associated with an increasing production of androgenic steroids. Adrenal androgen formation, termed adrenarche, may precede gonadal testosterone synthesis. Both adrenal and gonadal androgens exert their biological effects via the androgen receptor, a nuclear transcription factor modulating a specific transcription regulation of largely unknown genes. During puberty, virilizing actions such as genital enlargement and sexual hair growth can be distinguished from anabolic action such as the gain in muscle strength and general changes in body composition. Furthermore, androgens play a major role in the initiation and maintenance of spermatogenesis. Thus, different androgenic steroids play an important role in the process of puberty. The control of their biosynthesis, their possible differential action on the molecular level, as well as the different target organs in males and females are discussed.