The authors provide a systematic evaluation of the emerging multilevel paradigm in human resource management (HRM) research focusing, in particular, on multilevel mediation analyses of the HRM-outcomes relationship. They first distinguish different types of multilevel models and then identify a number of best practice theoretical and methodological criteria for the conduct of multilevel research derived from the literature. These criteria are used to analyze and evaluate all multilevel mediation studies ( N = 46) of the HRM-outcomes relationship published in 11 core management and HRM journals in the 2000 to 2016 period. The results suggest that progress in the application of the multilevel paradigm has been slow and uneven and that the new paradigm has not as yet taken firm root in the field of HRM. On the basis of this evaluation, the authors identify key areas for improvement in the application of the multilevel approach to the analysis of the HRM-outcomes relationship. In the process, they highlight important ways in which the further development of a multilevel perspective can enhance both strategic and employee-centered HRM research by contributing to a fuller substantive understanding of the processes and mechanisms through which HRM systems affect outcomes of interest at different levels of analysis.