The study investigates the efficiency effect of affiliation with the two strongest associations in Czech agriculture. These represent large-scale enterprises and individual farmers, respectively. The efficiency analysis is supplemented by analyses of incentives for associations' membership and farm characteristics decisive for membership choice. The results imply that political lobbying is the main entry incentive. Commercially-oriented individual farms which employ external workers are more likely to choose association membership, as are agricultural enterprises that specialize in livestock production or preserve a high share of employee ownership. We find that association membership has a significant positive impact on farms' performance, especially among individual farms. Non-members represent a more heterogeneous group. Nevertheless, the best non-members are able to achieve the production potential of association members.