This chapter examines communication in lizards, with a special focus on the role that sensory systems have played in shaping the evolution of signal physical properties. It reviews signal evolution as it relates to sensory response in a number of important sensory modalities. The chapter describes the basic response properties and their physiological underpinnings. It explores how sensory response properties have shaped the evolution of signal design and signal diversity. The chapter includes in this analysis considerations of the interacting effects of sensory response and signal context, signaling environment, and signal function. Visual resolution depends on the size and shape of the eye, the density of retinal photoreceptors, and the extent of neural convergence of photoreceptors onto ganglion cells. Since behavioral tests of color perception are very difficult to conduct for lizards, progress in understanding the role of sensory perception in the evolution of behavior has depended upon the ability to model the perception of color.