The simultaneous engagement in more than one form of media, known as media multitasking, is an ever-increasing phenomenon in our daily lives. Previous studies have associated media multitasking with lower self-control, greater sensation seeking and inattention, which could have detrimental effects on task performance. The current study examined task performance and mind wandering of heavy, intermediate and light media multitaskers as a function of task difficulty in an n-back task. The results showed that intermediate media multitaskers performed better than heavy media multitaskers at the more difficult than easier levels of the task. The performance of heavy and light media multitaskers did not significantly differ across difficulty levels. Intermediate media multitaskers also mind wandered less than heavy media multitaskers; however, their mind wandering did not differ from that of light media multitaskers. Thus, the results indicate an inverted U-shape relationship between media multitasking, task performance and mind wandering. The findings further suggest that the association between frequent media multitasking and greater mind wandering may be due to executive function failures as a result of insufficient cognitive control and distraction.