Employee time theft is pervasive and costly, but inadequately understood. Deploying a cognitive continuity perspective on the transition between non-work and work roles, we show time theft to be a psychological and behavioral continuance of past leisure at present work and propose that it results from leisure-to-work transition challenges. Results from two time-lagged studies revealed that employees with satisfying leisure experiences were more likely to find the transition back to work that they considered demanding and/or aversive more threatening and difficult to achieve. As a default response, they used retrospective mental time travel to continue in the past, engaging in emotional mind wandering about past leisure even after physically and temporally resuming work. These employees were further found to translate the wandering leisure cognitions into leisure-like and work-deviant time theft behaviors. Combined, our work yields theoretical and practical insights into employee work deviance from a transition perspective.