This chapter explores the structure, functions, and significance of Primary Fishermen Co-operative Societies (PFCS) in managing small-scale inland fisheries in India. It traces the evolution of the co-operative movement, the emergence of fisheries co-operatives, and their institutional foundations within the Indian socio-economic framework. Co-operatives, as one of the oldest forms of collective organization, aim to improve economic and social conditions through democratic governance and shared ownership. In India, PFCSs have become crucial in organizing inland fishers especially those from marginalized communities by facilitating access to credit, training, infrastructure, markets, and welfare schemes. Inland fisheries, which account for about 74.6% of national fish production, face critical challenges including environmental degradation, weak governance, fragmented support, and low investment. Using institutional data and case studies such as the Kalong Kapili Co-operative Society in Assam, this chapter highlights the importance of PFCSs in resource management, community empowerment, and sustainable fisheries governance.