GAO examined the potential effects of greenhouse gas emissions pricing on U.S. industries' international competiveness and trade measures being considered as part of U.S. Legislative proposals to address climate change. GAO examined (1) what is known about estimating industry effects; (2) examples of industries that may be vulnerable to a loss in international competiveness from emissions pricing; (3) trade measures and other approaches to address competiveness issues; and (4) potential international implications of trade measures.