Research on the relationship between emotions and job performance is ubiquitous, yet few scholars have examined the combined effects of different emotions. Drawing on the broaden-and-build theory and conservation of resources theory, we propose that employees’ daily emotion fluctuations will affect their service performance in opposite directions. Furthermore, we propose these effects will be moderated by psychological [i.e., regulatory emotional self-efficacy ] and physiological characteristics of the employees. Based on the experience sampling method, data obtained from 187 frontline employees of (...) 35 bank branches over 18 consecutive days supports our hypotheses. (shrink)