Research Highlights: This study reviews the available literature on processed non-timber forest products (NTFPs) in order to comprehensively identify relevant factors enabling or constraining their potential to contribute to rural development. Background and Objectives: NTFPs, such as wild foods, medicinal plants, and raw materials for handicrafts, make significant contributions to rural livelihoods. NTFPs can help fulfil households’ subsistence and consumption needs, serve as a safety-net in times of crises, and provide cash income. In particular, the processing of NTFPs has often been suggested to positively influence sustainable economic development in rural areas. However, despite rising interest and recognition of the potential contributions of such industries as key sources of employment and their strategic role in overall growth strategies of developing countries, many NTFP processing enterprises remain in the informal sector and an in-depth understanding of the underlying factors is lacking. This review aims to identify enabling and constraining factors affecting NTFP processing enterprises. Materials and Methods: Using systematic review methodology, studies investigating commercialized, processed NTFPs and their economic impacts have been identified and the current evidence base with regard to NTFP processing and small and medium sized enterprise (SME) development synthesized. Results: Despite the diverse nature of NTFPs, a number of constraining and enabling factors affecting NTFP processing and commercialization were identified. The former includes aspects such as the lack of resource access (finances, skills, technologies, etc.), market information, and basic infrastructure; the latter, amongst others, the role of key entrepreneurs; and cooperation across the value chain, amongst producers, and among members of the institutional environment or an abundant resource base. Moving from small-scale NTFP commercialization in local markets to more mature NTFP value chains reaching export markets, the increasing role of cooperation and having a supportive institutional framework in place, becomes apparent. Conclusions: Overall, successful NTFP processing strongly depends on the socio-economic and environmental context in question, requiring a holistic approach tailored to the respective context and value chain.