The research aimed to reveal the members’ willingness to invest capital in the Agricultural Producer Union (APU) and the factors influencing their decisions. The main data of the study obtained through the surveys from 420 members of the APU. Members’ willingness to invest capital in their unions and effective factors were determined using the Contingent Valuation Method and the Random Effects Tobit model, respectively. The research revealed that 44% of the union members were willing to make an average contribution of 355 TL to their unions. Random Effects Tobit model results revealed that member's trust, membership fee, participation in trainings, memberships of livestock union, apple and beekeeping, export crops through the union, attending the general assembly, level of education and agricultural experience positively affected the willingness to invest capital, while membership of the organic hazelnut and vegetables union, gender, management experience, age and total income negative affected the willingness to invest capital. In order to increase members’ willingness to invest capital to their unions, members’ trusts and participations in the training activities and administration of the unions should be increased.