The red-sided garter snake, Thamnophis sirtalis parietalis is an ideal model for the study of chemical or pheromonal communication in vertebrates. Results of long-term field and laboratory investigations of the chemical ecology of these unusual animals is summarized. These studies include a description of the characterization of the female attractiveness pheromone that serves to induce male courtship behavior. The male sex recognition pheromone system that identifies males as inappropriate individuals to court is also described. She-males, individual males that are courted as if they were females, seem to possess semiochemical components intermediate to both males and females. Finally, investigations of the species-specific nature of these pheromones indicate that chemical differences exist in the methyl ketones of all species examined to date.