Recent studies have focused on the study of social networks among local resource users, but few have attempted to study co-management networks. The objective of the research was to assess the Chilean shellfish co-management system from an organizational network perspective. Starting with one detailed case study, representatives of 38 small-scale fisher associations from two administrative regions were interviewed to investigate: (1) networks of actors in each co-management case, (2) the functions of these actors in co-management, and (3) fisher perceptions about Chile's co-management arrangement. Results indicate that decision-making is highly centralized and power is concentrated in government, with little horizontal exchange and cooperation among fisher associations. However, the network approach indicates the presence of a rich set of players, some seven sets of actors by function. Grassroots management innovations are hampered by the existing co-management structure, suggesting that the system may benefit from a modification of the policy to allow greater learning-by-doing and flexibility. © 2010 Elsevier Ltd.