Over the past 10 years a plethora of research has been conducted seeking to establish a relationship between human resource (HR) practices and firm performance. While this research has demonstrated promising results, a significant number of problems exist. This paper seeks to identify the theoretical and empirical challenges facing researchers who wish to further establish the impact of HR practices on firm performance. We conclude with some recommendations for future research in this area that might more accurately assess this relationship in ways that will be useful for both researchers and practitioners.