["Kyklos, EarlyView. ", "\nABSTRACT\nAgricultural cooperatives represent a promising way of improving the quality of life of half a billion smallholders, who account for the vast majority of the world's food production. Yet, little is known about the institutional factors that explain the potential benefits of being a member of a cooperative. As neither panel data nor comprehensive surveys are available from a cross‐country perspective, our study uses a meta‐analytical framework to fill this gap. We build a large database on the effects of cooperatives on their members, which consists of 1370 parameter estimates (i.e., outcomes) from 110 academic studies conducted in 32 countries between 1988 and 2018. The descriptive analysis suggests that agricultural cooperatives generally have a positive impact on the welfare of their members. The main analysis, conducted using a heteroskedastic ordered probit model, shows that a stable legal system, especially in non‐democracies, amplifies the positive impact of cooperatives on their members. We also find that cooperatives that are part of a federation have a higher probability of reporting a positive outcome, but only when they operate in democracies, highlighting the risk of political capture in non‐democracies.\n"]