This diary study investigates why and when multitasking impairs employees’ work-related flow and subjective job performance. Drawing on Lazarus and Folkman’s transactional model of stress and coping, the study proposes that employees’ appraisal of daily tasks (less challenging, more hindering) explains the negative impact of multitasking. Daily work engagement is expected to buffer these negative effects. Results from 33 food industry professionals over 4 weeks support the hypotheses: high task fragmentation led to less flow and lower performance; appraisal of tasks as less challenging (but not more hindering) explained impaired flow; and daily work engagement buffered multitasking’s negative impact on flow. The study offers ecologically valid insights into when multitasking backfires.

Helen Pluut, Maral Darouei, Marijn Eveline Lidewij Zeijen