Building on affective events theory (AET; Weiss & Cropanzano, 1996), the present research examined the short-term within-person effects of social conflicts with supervisors at work (SCSs) on followers’ state negative affect (NA) at home. Moreover, it was examined whether personal (i.e., core self-evaluations, CSEs) and environmental (i.e., procedural justice perceptions, PJPs) factors would moderate the SCSs–NA relationship. Hypotheses were tested with a diary study incorporating data from 98 civil service agents over five consecutive working days. Hierarchical linear modeling revealed that on the daily level, SCSs were related with employees’ NA before bedtime. Furthermore, results provide support for the moderating role of CSEs and PJPs in the SCSs–NA relationship. These findings show that the detrimental effects of SCSs are not restricted to the work context but spillover to employees’ private lives and help us to understand when SCSs are particularly detrimental for employees.