Research on the hormonal basis of sexual differentiation of mammalian behavior and its neural substrates constitutes an important chapter in the study of neural development that has led to important insights into how to conceptualize sexuality. Here research on sexual differentiation of avian social behavior is discussed with an eye toward potential insights into avian sexuality. Hormone manipulation experiments with Japanese quail (Coturnix japonica) and zebra finches (Taeniopygia guttata) reveal dissociations between different components of sexual and social behavior. None of the components of the male behavioral phenotype appear to be organized by androgens. Avian sexuality arises from multiple processes and pathways that appear to differ for mating behavior, sexual partner preference, and pairing. This provides the mechanistic bases for changes in social behavior in the course of avian evolution.