The presenteeism literature to date has largely focused on the negative aspects of presenteeism. Little is known about the potential functional or positive aspects of presenteeism. Drawing on the social cognitive framework of presenteeism, we examined the positive effects of presenteeism on performance evaluation in the context of high work demands. Across two experimental scenario studies (Studies 1a and 2) and two time-lagged field studies (Studies 1b and 3), we found that presenteeism was beneficial for employees' performance evaluations, especially under high work demands. Furthermore, we found that employees' affective commitment explained why presenteeism had a positive effect on performance evaluations under high work demands. Building on trait activation theory, we further demonstrate that proactive coping employees were more likely to be activated to commit presenteeism and to subsequently attained better job performance under high work demands. Taken together, our results illustrate when and why presenteeism can lead to better performance evaluations, as well as who may benefit from the act of presenteeism. These findings elucidate the functional or "good" aspects of presenteeism. Implications for theory and practice are discussed.