We examine the effects of entrenchment on corporate investment and firm performance. To achieve identification, we use a novel measure of entrenchment and an instrumental variable based on firms’ IPO cohort. We find that entrenchment reduces capital expenditures, R&D, and productivity, weakens a firm’s competitiveness in the product market, and diminishes firm value. These findings are consistent with the shirking hypothesis that entrenchment enables managers to slack off and dodge responsibilities of overseeing investment projects.