Androgens have diverse effects at both a physiological and behavioural level. These steroid hormones are present right from the first weeks of gestation and, in addition to playing a key role in the development of the male sex organs (both internal and external) are also involved in the development of the central nervous system in both males and females. In this book, the authors present current research in the study of androgens including androgen deprivation therapy for advanced prostate cancer; and the relationship between androgen levels and diverse cognitive abilities and social behaviour in childhood.