During the pre-structural adjustment era, many governments from developing countries supported agricultural producer organizations (POs). These organizations, however, often failed to provide desired services to members due to political interference, internal governance and managerial problems. Nevertheless, government withdrawal following market liberalization reforms left an institutional void. Drawing from experiences in Africa and other regions, this chapter reviews the roles that POs play and challenges that they currently face in improving members’ access to markets and agricultural technologies for enhanced food security and poverty reduction. Empirical evidence indicates non-exclusion of the poor from POs in many cases and such participation in POs has the potential to enhance members’ access to markets and technologies. However, POs face challenges of overlapping demands of social inclusiveness, empowerment and external competition. We conclude that democratic governance, homogeneous and optimal group size, transparency and market-orientation, can enhance POs’ performance. Donors and governments can stimulate the emergence and sustainable development of POs by investing in complementary infrastructure, capacity building, financial access and enabling regulatory and legal frameworks.