This study has three main aims: 1) The collection of theoretically informed empirical data on British interest groups; 2) The comparison of that data with comparable US material; 3) Improvement in understanding of decisions by potential members about joining interest groups. Membership characteristics of survey groups (i.e. FOE, Amnesty, NFU (Scotland), NFU (Countryside) etc.); motivation for joining; method of joining; demographic information - membership profiles.