Mindfulness is an inherent human capacity that is characterised as present moment awareness while maintaining an accepting and nonjudgmental stance. Mindfulness is related to better self-regulation and it enables individuals to refrain from behaviour that is driven by automaticity and impulsivity. While this is a capacity that can be beneficial in many jobs, we do not fully understand the work situations in which mindfulness may be helpful or the conditions under which mindfulness-based interventions (MBIs) improve critical outcomes such as mental health and performance. Research investigating the potential and limits of mindfulness in today’s challenging world is therefore warranted. This thesis set out to examine mindfulness in various contexts to investigate its potential mental health and performance benefits across different populations (N=564) distributed over five different studies. These five studies involved three different samples including employees (n=301), youth (n=239) and trainees (n=24). Cross-sectional survey designs and experimental intervention studies were used to investigate when and for whom mindfulness is beneficial. Hierarchical and stepwise multiple regression analyses, an ANCOVA and the Wilcoxon-signed rank test were applied to analyse data. It was found that mindfulness can help to buffer the negative effect of inauthenticity on depression in a sample of employees. Furthermore, more mindful employees showed a higher readiness for change in times of organisational change, but only when levels of well-being are high and distress is low. Having established that mindfulness can be beneficial in the workplace, it was investigated whether low-dose MBIs are effective in enhancing mental health and attentional performance. It was found that a low-dose-MBI could protect from performance decline in times of demanding training with positive effects on well-being at follow-up. Moreover, a low-dose MBI alleviated distress, but only for those who had higher levels of mindfulness and well-being at baseline. Finally, the contribution of different mindfulness facets to well-being and distress was investigated. The results demonstrated that the mindfulness facet Nonreacting was the main predictor of well-being, while the facet Acting with awareness was the main inverse predictor of distress.Overall, the findings of this thesis show that mindfulness can help employees to deal with demands at work, such as organisational change, and it can enhance well-being and reduce distress. However, mindfulness may not be beneficial under all conditions and for everyone. Organisations who aim to use interventions should carefully assess employees’ current levels of mindfulness and well-being to assign them to the right intervention format.