SMEs are the lifeblood of economies around the world. They play an important role in productivity growth, which is crucial for developed economies as they adjust to major trends such as the industrial revolution, an aging population, and changes in the nature of work. This study maps the SME productivity research landscape by way of a systematic literature review focusing on the direct, indirect, as well as mediating/moderating factors that enable or constrain productivity in SMEs. We review 109 empirical studies and highlight the fragmented nature of the extant research in this field. Our thematic analysis identifies six key themes, namely organizational environment, organizational capabilities, investments, types of innovation, external knowledgebase and commercialization. By taking stock of existing knowledge, we highlight critical gaps and methodological issues that limit our understanding of SME productivity. We propose a future research agenda to address current shortcomings and advance knowledge on this topic. Implications for policy are also discussed.