This chapter explores the dynamics of productivity growth in manufacturing plants, contrasting traditional models that assume identical, perfectly competitive firms with more nuanced models that account for firm heterogeneity. The authors use the Longitudinal Research Database (LRD) to analyze the productivity distribution and dynamics of plants over time, focusing on the contributions of entry and exit, persistence, and plant-level factors to industry productivity growth. Key findings include: 1. **Entry and Exit**: Entry and exit play a minor role in industry growth over five-year periods. 2. **High-Productivity Plants**: Increasing output shares in high-productivity plants significantly contribute to industry productivity growth. 3. **Persistence**: Plants at the top of the productivity distribution tend to maintain their position due to strong firm effects. 4. **80s Productivity Surge**: The manufacturing sector experienced a productivity resurgence in the 1980s, with greater mobility among plants compared to previous decades. 5. **Wage and Productivity**: There is a strong correlation between plant-level productivity and wages, suggesting either high-skill hiring or higher wages for workers in high-productivity plants. 6. **Plant Fixed Effects**: Persistent differences in management ability and workforce quality can explain the distribution of productivity across plants. 7. **Model Decomposition**: The productivity distribution can be explained by random shocks, random growth, vintage capital, or permanent plant heterogeneity. The vintage capital model and plant fixed effects are particularly relevant. The chapter concludes by discussing the implications of these findings for policy, emphasizing the importance of allowing high-performing plants to grow and the need to consider the complex dynamics of plant productivity in antitrust and other policy analyses.This chapter explores the dynamics of productivity growth in manufacturing plants, contrasting traditional models that assume identical, perfectly competitive firms with more nuanced models that account for firm heterogeneity. The authors use the Longitudinal Research Database (LRD) to analyze the productivity distribution and dynamics of plants over time, focusing on the contributions of entry and exit, persistence, and plant-level factors to industry productivity growth. Key findings include: 1. **Entry and Exit**: Entry and exit play a minor role in industry growth over five-year periods. 2. **High-Productivity Plants**: Increasing output shares in high-productivity plants significantly contribute to industry productivity growth. 3. **Persistence**: Plants at the top of the productivity distribution tend to maintain their position due to strong firm effects. 4. **80s Productivity Surge**: The manufacturing sector experienced a productivity resurgence in the 1980s, with greater mobility among plants compared to previous decades. 5. **Wage and Productivity**: There is a strong correlation between plant-level productivity and wages, suggesting either high-skill hiring or higher wages for workers in high-productivity plants. 6. **Plant Fixed Effects**: Persistent differences in management ability and workforce quality can explain the distribution of productivity across plants. 7. **Model Decomposition**: The productivity distribution can be explained by random shocks, random growth, vintage capital, or permanent plant heterogeneity. The vintage capital model and plant fixed effects are particularly relevant. The chapter concludes by discussing the implications of these findings for policy, emphasizing the importance of allowing high-performing plants to grow and the need to consider the complex dynamics of plant productivity in antitrust and other policy analyses.