Ten fishery cooperatives of the Pacific coast of Mexico were studied to examine reasons for successful community-based management of the fishery commons. The cooperatives hold exclusive rights to ‘concession’ territories for major fisheries and are linked by geographic adjacency and through a federation. The case study underscores the role of factors such as smallness of scale; the productivity, visibility and legibility of the resources and fisheries involved; clarity of social and territorial boundaries; adjacency and linkages among territorial units; a strong sense of community. The cooperatives also made considerable investments in attaining high levels of knowledge, leadership, transparent and democratic decision-making, and “vigilance,” or enforcement of the rules and the running of the organization. The study also shows the workings of windows of opportunity and experience with environmental change in the development of strong and adaptive capacities for co-management between local organizations and government agencies. Although particular histories and larger legal, political, and cultural contexts matter, the Mexican case supports arguments for greater community-level engagement in “catch share” and territorial management throughout the Pacific.