Since the global financial crisis in 2008, companies are increasingly interested in psychological resilience. This interest has been fuelled by the COVID-19 crisis. The central question in research regarding resilience is why some people successfully adapt to stressful events/circumstances (stressors), whereas others do not. This thesis aims to gain more insight into psychological resilience: how to understand this phenomenon and how to effectively enhance it.In the occupational context, many people seem to regard resilience as a (developable) personal attribute. This thesis shows that this view is outdated. Rather, it should be understood as a dynamic process by which people adapt to a stressor. To explain this process, this thesis presents a new model: the Psychological Immunity-Psychological Elasticity (PI-PE) model. This model shows how the process of resilience is triggered by a specific stressor, how this stressor can disrupt an existing psychological equilibrium and which pathways people may follow to either maintain, restore, improve or alter this equilibrium. The question that companies nowadays struggle with is how to effectively enhance resilience in their employees. To gain more insight into this question, this thesis first investigates what a resilience-building programme entails by deriving twelve criteria for these programmes from a systematic literature review regarding the definition, conceptualization, measurement and enhancement of psychological resilience. These criteria address, for example, the necessity to depict and explain the process that people go through in order to adapt to a stressor and to describe how resilience will be defined, measured and enhanced as a dynamic process. Secondly, this thesis identifies five approaches to enhance the dynamic process of resilience in a work context: a tolerance-enhancement approach, a narrative approach, a measured approach, a personal resource-based approach and an environmental resource-based approach. These approaches were derived from the PI-PE model. Thirdly, this thesis describes a systematic literature review regarding the effectiveness of psychological resilience-building programmes in the work context. This review showed that these programmes can be effective. However, almost none of these programmes were up-to-date, in that they did not regard resilience as a dynamic process. Finally, this thesis investigates the effectiveness of the resilience-building programme ‘ResilienceWise’. This programme meets the aforementioned twelve criteria and aims to enhance resilience resources in health care office workers facing organizational change. The effectiveness of this programme was demonstrated in two quasi-experimental field studies using a 2 (experimental and control group) x 3 (pre-test, post-test and three-month follow-up) design. The results show that this programme was especially effective in enhancing goal-related resources, such as hope, self-efficacy and purpose in life, and that this enabled office workers to better adapt to organizational change. Factors that may contribute to programme effectiveness are programmes that meet the aforementioned twelve criteria, focus on a specific stressor, use a single programme approach and use an individual mode of delivery. When it comes to resilience coaching programmes, the strength of the coaching relationship is a factor worth exploring.Taken together, this thesis sheds new light on psychological resilience and ways to build it.