One increasingly important driver for innovation is sustainability, a concept which aims to integrate ecological and social dimensions into conventional management. Whereas prior research on sustainability-oriented innovation (SOI) has often dealt with innovation processes in large companies, the last decade has also generated broad knowledge on SOI in small and medium-sized enterprises (SMEs). The paper aggregates this scattered knowledge through a systematic literature review. Through consulting research databases we have identified and analyzed 82 key journal articles. The subsequent thematic analysis focuses on SOI practices with regard to product and process innovations, on the one hand. On the other, we highlight the role of different parties that may facilitate or are involved in innovation processes in the context of SOI in SMEs.