Cognitive reappraisal can benefit employees, in terms of their emotional health. However, we propose that reappraisal can also entail hidden costs. Drawing on social-functionalist emotions theory, we posit that the use of reappraisal to control negative self-conscious emotions (guilt and shame) results in both positive employee outcomes (increased satisfaction, decreased burnout) and negative employee outcomes (increased counterproductive workplace behaviors (CWBs)). In Study 1, employees who used reappraisal to control guilt and shame were more satisfied and less burnt out, but also more likely to engage in CWBs. In Study 2, employees described what CWBs they would engage in if they faced no consequences: those using reappraisal to control guilt and shame reported more unethical CWBs and a greater willingness to actually perform the behavior. Study 3 assessed working MBA students in a live interaction (a heated negotiation), finding those who used reappraisal to control guilt and shame behaved more unethically. Studies 4 and 5 experimentally manipulated the use of reappraisal to control guilt and examined its effect on CWBs. Individuals in the reappraisal condition were more likely to withhold valuable resources from task partners (Study 4) and cheat on a work task (Study 5) than individuals in a control condition, providing causal evidence that reappraisal led to more CWBs.