AbstractResearch question/issueThis study examines whether there is decoupling between how firms communicate about corporate social responsibility (CSR) and what firms do in terms of CSR. We argue that this CSR decoupling is driven by the CEOs' cognitive biases. Specifically, we propose that overconfident CEOs increase CSR decoupling.Research findings/insightsWe tested our arguments in a sample of S&P 500 firms for the period of 2006–2014. We find that CEO overconfidence is positively related to the decoupling between the optimistic tone of CSR reporting and the firm's actual corporate social performance. However, the board of directors mitigates the effect of CEO overconfidence on CSR decoupling when outside directors have CSR expertise and ownership incentives.Theoretical/academic implicationsPrevious studies have suggested that CSR decoupling is a function of opportunistic management that can be constrained by external monitoring. We examine CSR decoupling as a function of cognitive biases (such as overconfidence) that can be constrained by internal monitoring.Practitioner/policy implicationsThis study provides insights into the conditions when CSR information released by the firm is symbolic. Practitioners may prevent such symbolic CSR reporting by imposing effective oversight by the board of directors.