Organizations are paying greater attention to the potential advantages that can be achieved by adopting a more strategic approach to the procurement of services. Despite services being very different from physical items in many respects, and despite their outsourcing having achieved limited gains, the procurement of services remains under-researched. To address this challenge and develop a strategic platform for new directions in future research in the area, this paper undertakes a systematic literature review of 51 articles published in 21 peer-reviewed academic journals. It reviews the applicability of supply theories to services sourcing, and compares and demonstrates the distinctiveness of services purchasing through problematizing the literature reviewed. A descriptive and thematic analysis concluded that services procurement can be classified into seven research domains: 'service production', 'governance', 'purchasing approach', 'supplier selection', 'performance management', 'the service triad' and 'specification of requirements'. We offer a comparative framework of the services procurement process and emphasize different supply practices. The provided research directions assist scholars in identifying avenues for integrating and expanding existing knowledge.