Polychronicity and multitasking have been described as being indispensible in work today because they enable people to use their time flexibly and effectively. We conducted a diary study among 93 employees during the mornings and evenings of 5 consecutive workdays (n = 418 observations). The study used hierarchical linear modeling with polychronicity and other personal characteristics at the person level, and multitasking behavior along with multitasking opportunities, interruptions, and unplanned work as antecedents, and affective well-being and self-rated performance as outcomes at the day level. We found several relations between antecedents and multitasking, as well as between multitasking and consequences. Polychronicity interacts with these relationships, such that polychronic individuals' affective well-being and self-rated performance are less affected on days with much multitasking compared to monochronic individuals.The continuingly changing demands in today's interconnected workplaces, the concentration of multiple duties in the same jobs, and the growing emphasis on speed and flexibility have made multitasking a necessity in the work of many (Appelbaum, Marchionni, & Fernandez, 2008). Current job descriptions often ask for multitasking ability. For example, typing in a job search on Monster.com with the keyword "multitasking" as requirement reveals thousands of hits. Despite the trend of recruiting multitaskers, there has been surprisingly limited research on multitasking in everyday work settings. Previously, multitasking has been conceived as a cognitive ability or as a cognitive process and has mainly been studied in laboratory environments within very short time windows (seconds, minutes). Studies aiming to understand multitasking in everyday work-life are rather scarce, but they are highly needed because of the growing prevalence and significance of multitasking in organizations. Adding to the outcomes of research on multitasking in lab settings, this study contributes to the understanding of multitasking by including the context of a work setting and by examining changes in multitasking and its effects over the course of several days. As far as we are aware, this study is the first study to investigate multitasking in the workplace, looking at variations in multitasking across working days. Our aim is twofold: first, a better understanding of multitasking, its personal and workplace antecedents, and its consequences for performance and affective well-being; second, clarifying the role of polychronicity, Correspondence should be sent to