Wildlife species have been recognized as sentinels of environmental health for decades. In fact, ecological data on various wildlife populations provided the impetus for banning some organochlorine pesticides over the last few decades. Alligators are important sentinels of ecosystem health in the wetlands of the southeastern United States. Over the last 15 years, a series of studies have demonstrated that environmental exposure to a complex mixture of contaminants from agricultural and municipal activities alters the development and functioning of alligators' reproductive and endocrine systems. Further studies of basic developmental and reproductive endocrinology in alligators and exposure studies performed under controlled laboratory conditions support the role of contaminants as causal agents of abnormalities in gonadal steroidogenesis and in reproductive tract development. These studies offer potential insight into environmentally induced defects reported in other wildlife and human populations exposed to a wide array of endocrine-disruptive contaminants.