Genetic and phenotypic analysis of strawberry notch suggests that its gene product is required during embryogenesis and oogenesis, and for the development of the eye, wing and leg. Several lines of evidence suggest that strawberry notch participates together with Notch in many common pathways. A number of strawberry notch mutant phenotypes are similar to those of Notch mutants and can be rescued by an extra copy of wild-type Notch. In addition, mutations in strawberry notch interact strongly with Notch mutants in a tissue-specific manner. Mutations in the strawberry notch and Notch loci also show very similar interactions with genes like Hairless, Delta, groucho, Serrate, and deltex that have all been proposed to participate in Notch related pathways. The genetic evidence presented here suggests that strawberry notch participates with members of the Notch pathway in facilitating developmentally relevant cell-cell communications.