Does monitoring workers improve or impair their productivity? Existing studies offer conflicting predictions. Using personnel and operational data from an Indian garment manufacturing plant, we examine how an RFID monitoring intervention on three of the plant’s twelve production lines affected productivity. We find that the effect of monitoring varied by the complexity of the work performed. Using variation in work complexity both across and within production lines, we find that monitoring significantly increased productivity for simple work but significantly decreased productivity for complex work. We contribute to research on monitoring and productivity by demonstrating how key job characteristics that make work meaningful, such as complexity, can moderate the effect of monitoring on productivity by affecting workers’ intrinsic motivation. Results also suggest that not only does the Hawthorne effect exist, but its direction can be positive, negative, or neutral depending on work complexity.