Environmental chemicals with hormone-like activity can disrupt programming of endocrine signaling pathways during development and result in adverse effects, some of which may not be apparent until much later in life. Recent reports link exposure to environmental endocrine disrupting chemicals during development with adverse health consequences, including obesity and diabetes. These particular diseases are quickly becoming significant public health problems and are fast reaching epidemic proportions worldwide. This review summarizes data from experimental animals and humans which support an association of endocrine disrupting chemicals, such as diethylstilbestrol, bisphenol A, phytoestrogens, phthalates, and organotins, with the development of obesity. Potential mechanisms are summarized and future research needs are discussed.