It is essential to understand how teachers cope with stress and how this affects their well-being as teachers work in very demanding environments. The study employed the transactional model of stress and coping as a theoretical framework to investigate the relationship between the Psychological Capital dimensions (self-efficacy, hope, resilience, and optimism), future-oriented coping (proactive and preventive coping), and work-related well-being (job satisfaction and work engagement). An online survey was completed by 213 secondary school teachers in Germany. Multiple hierarchical regression analyses indicated that optimism and self-efficacy were significant predictors of proactive coping, and hope predicted preventive coping. Optimism, hope, and resilience had a significant impact on job satisfaction. Furthermore, hope, optimism, and proactive coping significantly predicted work engagement. Proactive coping mediated the relationship between teachers' self-efficacy and work engagement as well as between optimism and work engagement, whereas preventive coping was not a significant mediator. The results imply that developing the Psychological Capital dimensions and proactive coping through interventions can be a valuable avenue to increase teacher well-being.