Test of the applicability of the hormonal theory of sex-dimorphic behaviour to adult women is achieved in this study by assembling measures of prenatal and adult androgen exposure, and a broad measure of gendered behaviour on a sample of white women aged 27-30. Androgen exposure in the second (and no other) trimester of fetal life, combined with and in interaction with adult androgens, masculineses women's behaviour and explains a substantial proportion of the within-sex variance in women's adult gendered behaviour.