An interdisciplinary integrative approach must be utilized in the study of psychosexual differentiation. The approach must capitalize on data derived from non-human models, from experiments of nature, and from experiments of nurture. Studies from non-human primates strongly suggest the influence of prenatal sex hormone levels on postnatal sexually dimorphic behaviours. Starting from this basis we have studied sixty young adult men whose mothers received, during pregnancy, diethylstilboestrol, diethylstilboestrol and natural progesterone, natural progesterone, or synthetic progesterone. They have been compared with matched controls not exposed in utero to exogenous hormones. Studies of socialization patterns must document the differential developmental experiences, if any, of children with atypical and typical sex-typed behaviours. To this end, we are studying 60 boys whose behaviour before puberty was decidedly feminine, and their parents, and contrasting them with masculine boys and their parents. We are also studying 50 girls whose behaviour before puberty was 'masculine', and contrasting them with 'feminine' girls. Additionally, we are studying the sexually dimorphic behaviour of children of sexually atypical parents. The parents have either undergone sex-change surgery (male-to-female or female-to-male) or are homosexual. Data from the three studies are presented. A call is made to researchers working with non-human primates to test and extend these findings.