Sustainable use of nontimber forest products (NTFP) in Amazonia, the World’s largest remaining contiguous rainforest, largely rests upon understanding patterns of resource use involving rural livelihoods to better inform conservation science. Brazil encompasses three-quarters of Amazonia, where non-indigenous semi-subsistence groups referred to as caboclos, outnumber native Amerindians by a factor of ten. The Brazilian government has committed to supporting participatory programs where monitoring biodiversity and co-management of natural resources are spearheaded by residents of sustainable-use protected areas. Notable among these initiatives is the Programa de Monitoramento da Biodiversidade e do Uso de Recursos Naturais em Unidades de Conservação Estaduais do Amazonas (ProBUC). ProBUC aims to 1) sensitize community residents to the importance of monitoring the state of natural resource use and establish norms for sustainable use, 2) train community residents to lead monitoring programs, 3) monitor species with high market potential (e.g. palms), 4) monitor species of special interest (e.g. red listed by IUCN), and 5) monitor land-use change. Since 2005, ProBUC has developed pilot projects in three conservation units, including two extractive reserves. Extractive reserves, defined as forest areas inhabited by extractive populations granted long-term usufruct rights to forest resources which they collectively manage, are among the most important protected area types, accounting for one seventh of Brazilian Amazonia. Here, we present the results of a two-year participatory monitoring program of extractive activities by caboclos inhabiting one of ProBUC’s pilot areas, the Uacari Sustainable Development Reserve, as well as the Médio Juruá Extractive Reserve, both within the Juruá River basin of western Brazilian Amazonia. We discuss the most important extractive activities for ~100 households, how socio-economic factors influence NTFP extractive patterns across households, and the benefits and constraints of using participatory approaches to monitor extractivism in Amazonia.