Abstract
High-quality HR practices do not always yield positive outcomes due to implementation shortcomings, which has led to the shift in focus from the content of HR practices to their process of implementation. Despite this shift, there remains a lack of systematic understanding of how and why implementation of HR practices succeeds or fails. To address this gap, a comprehensive review of effective implementation mechanisms, influencing contextual factors, and resulting outcomes is needed. Consequently, this study adopts a realist synthesis approach following the RAMESES publication standards to identify and synthesise existing evidence from empirical studies of HRM implementation. Reviewing 62 articles, we extracted and proposed four realist programme theories based on the process mechanisms attributed to actors of line managers, employees, senior managers, and HR departments. These realist programme theories explain how the process mechanisms bring about different outcomes in different contexts, hence, they enhance the understanding of ‘what works for whom in which circumstances?’ regarding HRM implementation.