Organisms exchange chemical signals that can shape a variety of behavioral and physiological responses; the latter have received relatively little attention. I will describe our recent studies in C. elegans that have demonstrated salubrious effects of male pheromones on the reproductive system of their mates. I will focus on our efforts to identify neuronal circuits responsible for sensing pheromones and relaying their signals to target tissues. Several mechanisms we found appear to be conserved among distantly delated animals, suggesting that they represent vestiges of a system that detected and implemented the effects of social signals in an ancient bilaterian ancestor.