Chemical signals in the body, in the brain, and semiochemicals excreted into the environment control the social lives of animals, impacting reproductive opportunities and competitive outcomes. I use lizards to examine the role of both endocrine and exocrine signals in regulating male-male and male-female interactions from an evolutionary standpoint. Territorial male lizards compete for access to females and other resources and the hormone arginine vasotocin (vasopressin) modulates competitive interactions via the visual sensory system, as demonstrated by the life’s work of Walt Wilczynski, but vasotocin may also impact chemosensory behavior during social interactions. Here, I demonstrate how vasotocin impacts chemosensory behavior during male-male interactions in green anole lizards, then compare these data to the impact of vasotocin in females on male-female interactions. I also discuss the future of the field of endocrine modulation of chemical communication in lizards.