Voluntary consumer decisions to purchase electricity supplied from renewable energy sources represent a powerful market support mechanism for renewable energy development. Beginning in the early 1990s, a small number of U.S. utilities began offering ''green power'' options to their customers. Since then, these products have become more prevalent both from utilities and in states that have introduced competition into their retail electricity markets. Today, more than 50% of all U.S. consumers have an option to purchase some type of green power product from a retail electricity provider. This report provides an overview of green power marketing activity in the United States. The first section provides an overview of green power markets, consumer response, and recent industry trends. Section 2 provides brief descriptions of the utility green pricing programs available nationally. Section 3 describes companies that actively market green power in competitive markets and those that market renew able energy certificates nationally or regionally. The last section provides information on a select number of large, nonresidential green power purchasers, including governmental agencies, universities, and businesses.