In this article we tried to discover the cooperative system as the third sector in industrialized countries. We researched the cooperatives in industrialized countries which have gained recognition as an economic and social force. Service cooperatives of farmers, craftsmen, traders, members of liberal professions (such as medical doctors, pharmacists, tax consultants), consumers and tenants have developed from modest beginnings into large-scale, professionally managed business ventures in full competition with commercial firms. While in many European countries cooperatives are considered elements of the private sector, in other countries (e.g. Belgium, France, Italy, Portugal, Spain) cooperatives, together with associations and mutual insurance organizations, are perceived as part of a new, alternative or “third” sector of the economy, referred to as “économie sociale”.