This study examines moral reasoning in boys (ages 5 through 9) to test the psychoanalytical predictions that their moral development is optimal when they live with two parents of different sexes. Moral reasoning levels of boys from lesbian two-parent families did not differ from that of boys in heterosexual two-parent families. The oedipal theory, that sons develop morality through castration fears and identification with a male parent, was not supported for this age group. Lesbian and heterosexual families did not differ in parents' teaching style about morality or in sons' interactional style. Implications of these findings for developmental theory, particularly psychoanalytic theory, are discussed in the context of a rapidly changing society in which traditional relationships between parents and children are being altered as well as the definition of family.