Testosterone (T) influences a wide variety of sexual and social behaviors, but the extent to which variation in muscle physiology underlies these behaviors is not clear. We investigated the effects of T on the morphology, physiology, and behavioral use of two muscles in green anole (Anolis carolinensis) and brown anole (A. sagrei) lizards. We examined the ceratohyoid, the muscle that moves the throat fan called the dewlap in social display, and the retractor penis magnus (RPM), a muscle that moves the hemipenes during copulation. We assigned males of each species to one of three treatment groups: high T males were gonadectomized and received a T implant; low T males were gonadectomized and received a blank implant; and control males underwent sham surgery, where their testes were left intact and they received a blank implant. Before surgery, males assigned to these groups did not differ in morphology or behavior, yet six weeks after hormone manipulation, high T males displayed their dewlap more frequently than low T males in both species. However, T affected dewlap size differently between the two species, with T exposure increasing dewlap size in green anoles but having no clear effect on brown anole dewlaps. We are currently measuring the sizes of the CH and RPM, the number and size of their muscle fibers, and androgen receptor expression in myonuclei. The results of this study will help us understand how T facilitates dynamic changes in muscles and the behaviors they support.