Commercialization of non-timber forest products (NTFPs) has been widely promoted as an approach to rural development in tropical forest areas. However, donor investments in the development of NTFP resources have often failed to deliver the expected benefits in terms of poverty alleviation and improved conservation of natural resources. In order to ensure that NTFPs fulfil their potential contribution to sustainable development, it is important to understand the reasons for success and failure, and the conditions under which NTFP commercialization can make a positive contribution to the livelihoods of the poor. This publication presents the findings of the CEPFOR project (Commercialization of non-timber forest products in Mexico and Bolivia: factors influencing success), a multidisciplinary research initiative involving partners drawn from the UK, Mexico and Bolivia. The research team critically examined the factors influencing successful NTFP commercialization and tested and further developed theory relating to the commercialization of NTFPs and rural development. Socioeconomic and market research examined the impact of different NTFP commercialization networks (value chains) on poverty reduction, women’s livelihoods, natural resources and rights and access of the poor, in eight communities in Bolivia and 10 in Mexico. The structure and function of 16 NTFP value chains were analysed, enabling identification of the attributes that make a chain successful.