Gray's reinforcement sensitivity theory (RST) describes two important personality constructs; sensitivity to reward and sensitivity to punishment. In two studies, we examine whether these constructs can be considered dispositions to work stress. Results of Study 1 (N = 105 employees in different occupations) indicated that employees with strong punishment sensitivity reacted more strongly to work stressors than others. This idea was confirmed in a longitudinal design in Study 2. Reward sensitivity was unrelated to stress in both studies. Overall, results strongly support the idea that punishment sensitivity is a dispositional source of work stress. Results further confirm that RST and its derived personality measures can contribute to theorizing about personality–environment interactions in a highly relevant daily setting, namely the working environment. Copyright © 2007 John Wiley & Sons, Ltd.