Successful conservation depends as much on people working together as it does on sound science and good governance. Research on cooperation in businesses, economics, psychology, and natural resource management has identified shared social and social-ecological dynamics, reviewed and categorized in this article that can create unwanted surprises and problems for conservation efforts. Cooperation may fail when: (1) individual and group benefits are in conflict (social dilemmas) or (2) social-ecological systems become caught in problem-causing and problem-enhancing feedbacks (SES traps). Knowing about and recognizing these dynamics can help decision makers to understand and change key elements of problems and learn from the experiences of others. Social dilemmas have winners and losers, and involve give-some or take-some choices; SES traps are lose-lose situations. Solutions to problems of cooperation in conservation contexts involve identifying the conservation objective and context, diagnosing systemic social dilemmas and SES traps, and developing practical solutions that work with group processes and individuals toward shared and positively reinforcing goals, goal structures, and expectations. Research on cooperation in conservation has largely ignored problems of scale, scaling, and group heterogeneity. The field would benefit from a shift from a probabilistic, empirical approach to a stronger theory-driven, mechanistic, and more diagnostic approach.