I analyze a green product market in which eco-labeling programs compete—programs certifying the environmental quality of the product to their respective standards. Specifically, I examine the strategic competition between an industry-sponsored program and a program sponsored by nongovernmental organization (NGO) in a duopoly product market where eco-labels are strategic variables for firms. In particular, I analyze the effects of such eco-label competition on environmental benefit and social welfare. I show that the eco-label competition may generate the same environmental benefit and generally increase social welfare relative to a single NGO label.