Despite the recent proliferation of research on media multitasking, a comprehensive meta‐analytic review of its effects has not been available. Based on a review of 49 media multitasking studies, this meta‐analysis showed that multitasking has negative effects on cognitive outcomes, whereas it has positive effects on attitudinal (or persuasion‐related) outcomes. Moderator analyses suggested that the negative effects of multitasking on cognitive outcomes varied by (a) user control, (b) task relevance, and (c) task contiguity. Specifically, multitasking had greater effects (a) when media users had less control over the media, (b) for tasks that were unrelated, and (c) for tasks that were physically distant. Implications for future multitasking research are further discussed.