In the face of a rapidly changing global climate, it is important to understand how thermal fluctuations and contaminant exposure interact to influence wildlife health. Species with temperature-dependent sex determination (TSD) may be especially vulnerable to the adverse effects of these anthropogenic influences due to their profound environmental sensitivity during development. In this study, we examine the interactive effects of ecologically relevant temperature regimes and embryonic exposure to the organochlorine pesticide metabolite, p,p’-DDE on the reproductive development of the American alligator (Alligator mississippiensis), a species with TSD. During incubation, alligator embryos were exposed to one of five thermal regimes – a constant female-promoting temperature (30˚C), a constant male-promoting temperature (33˚C), a constant intermediate temperature (31.2˚C), or a fluctuating temperature regime based on empirically derived nest temperature profiles with an amplitude of either ±0.6˚C or ±2.8˚C around a mean of 31.2˚C. At developmental stage 19, eggs were topically exposed to a vehicle control or one of two doses of p,p’-DDE (low dose, 0.1µg/g egg weight; or high dose, 1µg/g egg weight). Levels of circulating plasma sex steroids and gonadal expression patterns of genes involved in sex determination and reproductive development were examined in 10-day old alligator hatchlings. Effects of temperature and contaminant exposure on patterns of inter- and intrasexual variation in neonatal alligators provide insight into the persistent consequences of interacting anthropogenic stressors experienced during development in a wildlife model.