Research has focused on employee emotion regulation as a stable dispositional tendency. Yet effective and healthy emotion regulation requires flexibly choosing between different regulation strategies in response to various workplace situational demands. In this study, we investigate the between- and within-person emotion regulation differences of 83 frontline managers across 10 working days. Using affective events theory, we examine managers’ use of three main emotion regulation strategies (cognitive reappraisal, suppression, expression) in response to the negative affect they experience while engaging in various tasks, and the consequences for their daily stress. The moderating effects of four emotional intelligence abilities are also examined. Our results demonstrate negative emotions associated with work tasks are regulated in ways that are determined by stable, situational, and personal factors. Practical implications for organizations are considered. JEL Classification: JEL code - D23.