Abstract: The present paper illustrates the relationship between group heterogeneity and the success of collective action in addressing local common-pool problems which exist in the Al-Batinah fishery, Oman. The Al-Batinah coast is home to around 35 % of the country`s artisanal fishermen. During the last decade, the region has experienced a general decline in landings with the consequences of socio-economic disturbance and increased fishing pressure. Cooperative management to solve the problems of common pool resources has been widely promoted. However, cooperative management is difficult among heterogeneous groups of fishermen who vary principally with regard to their fishing skills, income and other socio-economic factors. The importance of the differences in the nature of interests of various individuals and how inter-individual variations impact some critical endowments are emphasized. Data for this paper was gathered through a pre-tested questionnaire from a cross sectional survey executed in three coastal towns in the Sultanate of Oman. The study findings revealed that the differences in objectives and interests created an obstruction to collective action. However, the same cannot be said regarding the differences in the distribution of income. Greater inequality does not necessarily lead to more efficient use of natural resources as predicted by Olson (Olson, 1965).