This paper examines the effects of gender inequality on prospects of cooperation and environmental sustainability. Gender inequality is a form of inequality that is interactive with but distinct from other forms of economic and social inequalities. It dwells not only outside the household but also centrally within it. It stems not only from pre-existing differences in economic endowments between women and men, but also from preexisting gendered social norms and social perceptions, that is, the inequality is also ideologically embedded. And it not only pre-exists in the noted forms, but can also arise from newly-defined rules and procedures that structure the functioning of the governance institution itself. All three dimensions of gender inequality can impinge on prospects for cooperation and efficient local commons management; and all are largely neglected in collective action literature on the commons. The paper also distinguishes between voluntary and non-voluntary cooperation arguing that cooperation need not always be a voluntary act. Cooperation may appear to exist despite inequalities and conflicts of interest within a community, because it is imposed by some on others through the exercise of social and/or economic power. The paper analyzes how these different aspects of gender inequality can impinge on collective action and the form it takes (voluntary or non-voluntary), and the likely outcomes for environmental sustainability. It does so by analyzing the experience of community forest management across India, drawing also on the author's recent field data from western India. In addition, based on the latter, it empirically tests the effects on rule formulation and forest quality of women's greater inclusion in the decision-making process of local commons governance.