ABSTRACT*The Swedish welfare system was developed in an incremental fashion in an interaction between the state and a range of voluntary organizations. Consequently, Swedish voluntary organizations do not quite fit accepted typologies, with regard to underlying normative principles, fields of activity and organizational forms. The absolute size of the Swedish nonprofit sector is comparable with that of other European countries. However, the bulk of its activity is within policy formulation, rather than service provision; concepts of membership and popular movement are central, and charitable organizations are marginal. The spread of existing organizational forms is reviewed, with particular reference to the role of cooperatives. New cooperative users' and producers' organizations play an important role in the current expansion of third‐sector organizations providing welfare services. Three case descriptions of new cooperative forms are appende