SMEs and Supply Chains: A Systematic Review of CSR Adoption and Scalability Models

Small and medium-sized enterprises (SMEs) constitute the majority of firms in most economies and are increasingly exposed to corporate social responsibility (CSR) expectations through supply chain relationships. Yet CSR adoption in SMEs is uneven, and many approaches promoted by large firms (e.g., extensive audits, complex reporting, costly certifications) are difficult to sustain at scale for resource-constrained suppliers. This systematic review synthesises evidence on how large-firm supplier requirements shape SME labour, safety, and environmental practices, and which low-cost, scalable CSR models are most feasible for SMEs. Following PRISMA 2020 reporting guidance, the review screened 240 records, assessed 50 full texts, and included 20 peer-reviewed studies (2006–2024). Thematic synthesis identifies four recurring mechanisms: (a) compliance-oriented pressure via contractual clauses, codes, and audits; (b) internalisation through owner-manager values and strategic opportunity; (c) capability constraints involving knowledge, systems, time, and finance; and (d) scalability through shared infrastructure, intermediaries, and collective action (clusters, cooperatives, and networks). Evidence suggests that supplier requirements can trigger minimum compliance but may also produce superficial adoption when capability support is absent. Scalable models emphasise shared audits, supplier development, peer learning, simplified metrics, and digital tools that reduce per-firm transaction costs. The review concludes with an integrated conceptual model and a research agenda focused on causal designs, multi-tier diffusion, and low-cost implementation pathways in low- and middle-income contexts.