Participatory Guarantee Systems (PGSs) are alternative certification schemes for organic products, built on trust and social networks, and intended for local markets. In contrast to third party export-oriented certification schemes, farmers working with PGSs are directly involved in the implementation of the system. Farmer-to-farmer peer-review is also an essential feature, built on equality and knowledge-sharing between the inspector and the inspected. The Maendeleo Group was one of the first organisation of farmers in Tanzania to implement a PGS and receive permission to use the East Africa Organic Mark on their produce.