The significance of the line manager's role in HRM implementation in Strategic HRM literature is well-established. However, uncertainties persist about what, when, and how, specifically line managers are involved in this process. This systematic review, drawing from the analysis of 89 articles, delineates "what" entails line managers' involvement in executing HR-related tasks, showcasing less pronounced participation in decision-making, financial authority, and knowledge transfer. "When" line managers are involved hinges on various factors—external, contextual, organizational, and notably individual considerations. Finally, "how" depends on partnership with HR professionals, employing adaptive strategies, and the agency of line managers. Based on our comprehensive analysis, the study developed an integrative framework identifying significant gaps in understanding what, when, and how line managers are involved in HRM implementation. Additionally, the paper proposes potential research inquiries within each domain to assist HR scholars in advancing this evolving research field.
