Mergers and acquisitions (M&As) are increasingly undertaken in both the private and public sector, as organizations vie for competitiveness within challenging economic climates. Yet, the social costs of M&As are rarely considered in the planning and implementation of these impactful organizational change processes. In this review, we take a social identity approach to M&As, exploring the impact of M&A activities on employees and their local communities. Specifically, we outline the pivotal role played by identity reputation and continuity, intergroup structure and processes, leadership and justice in managing employee adjustment during M&As. Throughout our review, we pay close attention to the managerial implications of our findings for strategic planning and best practices within M&A contexts. We conclude by outlining the implications of our review for the development of official guidelines and social policies around M&A implementation.Merger and acquisition (M&A) activities are one of the primary strategies for organizations to secure market competitiveness in an increasingly global market place Plan investments to manage human resources during the M&A Invest more time and resources into employees from the acquired (dominated) merger partner, i.e., those who experience a lower sense of continuity, than those from the acquiring organization Monitor levels of postmerger identification (e.g., employee surveys) in order to adjust intervention and communication strategies Tailor communication strategies for different change recipients.Communicate quickly with employees who are less-affected by the merger. Invest heavily into communication with employees who are more strongly affected by the merger. Additionally, invest in bottom-up communication channels that enable employees to voice concerns Facilitate the emergence of a positive transitional and future identity by promoting shared labels and positive collective visions of the new merged organization. Provide more autonomy to HR managers during the integration phase so that they can manage employee uncertainty and adjust their communication and training efforts in flexible ways. 2. Intergroup structure and processes