- Nudges are widely used and a broad literature documents that they successfully affect individual behavior. However, in most settings where nudges are needed to change collective action, teams – not individuals – determine outcomes. Because team decision making is pervasive, learning whether nudges work with teams in social dilemmas is important, especially when formal enforcement is difficult. Here, we show that a nudge increases team cooperation by 14 to 16 percentage points in a social dilemma among fishing crews at Lake Victoria, Tanzania. The nudge is particularly effective when team decisions are made by a team member with leadership experience. Our findings are a proof of concept that expands the toolkit of empirical researchers and policy makers that address social dilemmas among teams.