This book contains four related studies research the relationship of Human Resource Management and Firm Performance. Chapter 1 introduces the intermediary mechanism of intellectual capital, to understand how people management drives organizational performance. Chapter 2 is a two years long research project. Findings indicate that individual's intrinsic motivation has stronger impact on job performance than extrinsic motivation. Chapter 3 is a study about investigating the determinant factors of incentive pay schemes and the impact of variable pay on firm performance. Findings indicate that the primary determinant of incentive plans adoption is environmental variability, while the second is the innovative culture that embedded in the firm. As to the best predictors are environmental variability and the proportion of variable pay. Chapter 4 investigates how the client firms manage their agency workers. And whether different management practices result in different job performance outcome? The t test result shows that agency worker's job performance in firms with transferring to full time job scheme higher than that without. Some other managerial practices are included in the book.