摘要:We examine factors affecting entry and contribution to an association that provides different goods using social capital formed by heterogeneous firms that lobby in a political economy environment. We identify how associations attract the most productive firms or the least productive firms in an industry and explain how such associations differ in their intensive and extensive marginal contributions to social capital. We find that the level of regulatory stringency, association products including capital goods for members or lobbying to influence regulation, and government influenceability affect membership and contribution decisions. These results vary with firm productivity. Often, an increase in government influenceability increases social capital in associations composed of highly productive firms because they prefer to influence policy while less productive firms prefer more association‐produced production inputs. (JEL D71, D73)