Abstract: Understanding the internal mechanisms regulating female mate choice can provide great insights into identifying evolutionary targets of sexual selection as well as the underlying rules guiding behavior. In my lab, we investigate the basic brain and sensory processes underlying mate choice behavior in both swordtail fishes and poison dart frogs. Using genomic ( whole brain expression profiling), neural ( localization patterning via in situ hybridization) and sensory (perceptual manipulation) experiments, we have begun to identify internal processes that successfully predict female preference behavior. These insights have suggested that (1) there are stimuli-specific genomic networks associated with preference, (2) brain nuclei associated with preference are unique from those associated with receptivity, and (3) simple sensory biases (e.g. preference for brighter males) can potentially lead to complex evolutionary outcomes (e.g. changes in male hues). Our current and future research involve developing pharmacological and sensory manipulation experiments to test these emerging hypotheses as well as to test the generality of these mechanistic processes using comparative approaches.