Theoretical models in strategic human resource management research commonly include employee attitudes and behaviors as key mediating links between human resource practices and firm performance. However, almost all empirical SHRM work to date has ignored the mediating hypothesis and merely examined the direct relationship between HR practices and firm outcomes. The purpose of this study is to test the relationship between HR practices and employee attitudes and behaviors. Using a sample of 174 independent work groups, we examined the relationship between HR practices and collective behaviors (turnover and absenteeism) mediated by collective attitudes (job satisfaction and commitment). Results indicate attitudes partially mediate the relationship between HR practices and employee behaviors. The direct and indirect relationships identified in this study support the notion that attitudes and behaviors play a mediating role between HR practices and firm outcomes. These findings illustrate the varying impacts of HR practices and the importance of utilizing multilevel theory and methods.