Co-operatives are generally seen as the means for uplifting the condition of fishermen. Despite this apparent contradiction, there has been little research on the fishery co-operatives. This study aimed to fill the information gaps and provide a knowledge basis for intervention in the co-operative institution. Its broad objective was to analyse, using socio-economic approaches, the structure, strategies and performance of the Lake Victoria co-operatives and propose their potential roles and conditions for involvement in co-management of the fishery. This thesis has described the characteristics and strategies of the Lake Victoria fishery co-operatives. It has proposed an approach - the stakeholders? criteria - for evaluating co-operative performance. On the basis of the criteria, the factors affecting the performance of the co-operatives of Lake Victoria have been analysed. Three models in organizational theory have been used to explain further the performance factors. The study has suggested roles for co-operatives in co-management. This study was accomplished through the sponsorship of the European Development Fund, being part of its financial assistance to Lake Victoria.