Globalization is challenging the very core of cooperative governance and ownership decision, especially in Southern European countries, like Portugal, where a large number of producers are organized in traditional and Mediterranean-style agricultural cooperatives. This paper analyses the effects of governance and control variables related with size over two alternative indicators of performance: revenues transferred to members/patrons and capital structure. The results suggest that these cooperatives have difficulties being sustainable in the more competitive global wine markets, if they follow, essentially, a practice of maximum patronage refund, reducing their capacity to improve leverage and to finance more profitable, but risky, long run investments.