The choice between male and female development arises from a simple binary decision made in early development. Studies in a few model organisms led to a detailed understanding of the regulatory mechanisms that convey male or female identity at the cellular level. We have learned little, however, of how this information translates into the actual sexual phenotype with regionally dimorphic characters. Where does positional information come from and how does it integrate with the sex-determining pathway? A recent report sheds light onto this enigma and reveals possible intersections between sex-determining and homeotic pathways in Drosophila. Such intersections may also play an important part in evolution, providing a basis for phenotypic diversity among related species. BioEssays 23:304-306, 2001.