Membership in environmental groups and participation in environmental activism have grown dramatically during the past two decades. Militant environmentalists, a small segment of the environmental activist community, are increasingly becoming the focus of public interest and media attention. Environmental organizations such as Greenpeace, the Sea Shepherd Conservation Society, and Earth First have historically used dramatic direct action operations to accomplish their environmental agenda. Legal consequences of these operations have largely been limited to the prosecution of individuals. Concurrent with intensified interest in environmental activism, courts have expanded existing organizational liability doctrine to reach interest group organizations more easily than before. A corporate approach to nonprofit organizations and unincorporated associations, concerted action and agency doctrines, and liberal requirements for civil RICO (Racketeer Influenced and Corrupt Organizations) cases have been used to impose liability on organizations. The concomitant expansion of public awareness and legal liability should give notice to environmental organizations to prepare for the enhanced possibility of litigation due to member actions. 156 footnotes