Over the past two decades, a growing body of research on human resource management (HRM) has analyzed the relationship between international HRM and institutions. This work has primarily been informed by two leading streams of theory—organizational institutionalism and comparative institutionalism. However, these two dominant streams have seen much juxtaposition, but little logical integration. Moreover, scholars have paid little attention to the dynamics of contextualization (more specifically, institutional development and evolution), which limits the relevance of extant research. In this article, we review the extant literatures and their intellectual origins and develop an integrative research agenda that emphasizes the multilevel nature of HRM and evolution under external institutional change.