Interest groups have played a dominant if not determinative role in the "greening of America." Thus, that Lettie Wenner, a political scientist who has devoted much of her career to studying environmental issues (The Environmental Decade (1982) and One Environment Under Law (1976)), should publish a compendium describing such groups is an occasion for optimism. And, indeed, she does provide a useful reference tool for those seeking basic descriptions of these groups; yet, unfortunately, she does not offer a thorough or critical understanding of how they operate.