Despite decades of research, the key factors for success in mergers and acquisitions (M&As) and the reasons why M&As often fail remain poorly understood. While attempts to explain M&A success and failure have traditionally focused on strategic and financial factors, an emergent field of inquiry has been directed at the sociocultural and human resources issues involved in the integration of acquired or merging firms. This research has sought to explain M&A performance and underperformance in terms of the impact that variables such as cultural fit, management style similarity, the pattern of dominance between merging firms, the acquirer's degree of cultural tolerance, and the social climate surrounding a takeover have on the postmerger integration process. In this article, we attempt to take stock of, and synthesize, the findings from research on sociocultural and human resources integration in M&A, to identify conflicting perspectives and unresolved questions as well as several underresearched areas, and then use our analyses to propose an agenda for the next stage of research in this field.