Temperature-dependent sex determination (TSD) is a mechanism by which exposure to pivotal temperatures during embryonic development irreversibly determines sex. The sex of the endangered loggerhead sea turtle (Caretta caretta) is subject to TSD. In loggerheads, higher temperatures produce female turtles and lower temperatures produce male turtles. We investigate tissue- and temperature-specific gene expression within brain (n=7) and gonadal (n=4) tissue of male and female loggerhead hatchlings.