AbstractThis study examines how unionization affects firms' financial reporting. Using a regression discontinuity design, we compare practices of firms narrowly winning and losing union certification elections. We find that winning firms depress earnings significantly more by inflating discretionary expenses, particularly research and development expenses, to strengthen their bargaining positions with workers. We further show that this manipulation aligns with managers' financial incentives, career motives, and entrenchment levels. The paper highlights managers' strategic use of real earnings management in worker negotiations and provides causal evidence on how the dynamic relationships among managers, shareholders, and workers shapes firms' financial reporting.