We analyze venue choices by interest groups-the extent to which a group lobbies the Congress, executive branch agencies, and the judiciary-and develop two types of models tested with Jack Walker’s 1985 Study of Voluntary Membership Organizations. The first explains the degree to which a group is involved in each venue separately. The second examines a group’s level of institutional involvement in comparison to the other branches. What explains a groups’ greater utilization of Congress than the courts, of Congress than executive agencies, and of executive agencies than the courts?