Despite the proliferation of HRM research, only a small fraction explores the context of small and medium‐sized enterprises (SMEs). Where HRM in SMEs has received attention, the literature base remains fragmented and variable, comprising a plurality of definitions, explanations, and methods. To advance understanding, this paper uses a quarter‐century systematic review drawing on an evidence base of 137 peer‐reviewed articles. A cumulative framework is presented capturing key developments and synthesizing existing areas of research focus. Analysis of limitations and knowledge‐gaps finds a failure to differentiate across various types of SMEs, limited appreciation of SME characteristics and contextual conditions, and a dominance of managerial perspectives. An agenda for future research on HRM in SMEs is outlined with respect to definitional parameters, HR practices, HRM–performance, key determinants, and presenting issues. The paper concludes that SMEs offer a unique, fruitful, and timely context for investigations of HRM.