In this diary study, we investigated multi-level predictors of daily counterproductive work behavior (CWB) relying on the theoretical frameworks of affective events theory and the emotion-centered model of CWB. We assessed significant work events, event-based fairness perceptions, negative emotional reactions to work events, and employee CWB over a 10-day period. We tested within-person relations predicting CWB, and cross-level moderating effects of two emotion regulation strategies (suppression and reappraisal). Results from a multi-level path analysis revealed that significant work events had both direct and indirect effects on negative emotional reactions. Further, negative emotional reactions in turn mediated the relationships between significant work events and all forms of daily CWB ...