A broad arch of deforestation spans the lower Brazilian Amazon, cutting through the State of Mato Grosso. The forceful expansion of soybean plantations led by global markets is displacing family farms or incorporating them into out-growing schemes. Commodity plantations are pushing cattle ranching further into the forests. Logging is also opening up new access at the frontier. As associations endeavor to strengthen the voice of marginalized groups their role and functions continue to evolve. This report analyses eight active associations along the BR 163 highway in Mato Grosso. It assesses the factors that have allowed them to function and spread benefits to the poor. It also identifies the types of external support that have proven useful.