Mindfulness is an inherent human capacity: a state of consciousness which everyone has the ability to experience, and which is consistently related to positive psychological and physical outcomes. Sport coaching is a challenging occupation, known to be demanding and, at times, stressful. This thesis explores different ways in which mindfulness assists sport coaches to maintain wellbeing, in the face of the demands and challenges of their coaching work. The thesis comprises three empirical studies, each investigating relationships between coaches’ mindfulness levels and wellbeing related outcomes. Each uses a different research design and method, providing unique insight on the relationship between coach mindfulness and wellbeing. The first study, using cross-sectional data collected from 143 New Zealand-based coaches working at a range of coaching levels, tests for relationships between mindfulness, and recovery from work demands. Different conceptualisations of work-related rumination are included in the model as mediator variables. The second study builds on the first, but utilises an intensive longitudinal design. This study draws on daily data collected from a sample of 46 New Zealand based coaches, over a period of 28 consecutive days. Multi-level modelling is used to test for relationships between fluctuations in individual coaches’ daily mindfulness levels, and subsequent changes in work related rumination and in work-recovery related outcomes. The third and final study also assesses the daily data, this time analysing brief qualitative diary entries relating to both stressful and positive daily events. Multi-level logistic regression is used to test for relationships between daily mindfulness levels, and the content of the daily diary entries. Results from the three studies show mindfulness to be influential both in terms of the stress that coaches experience, and in their ability to recover from the daily demands of their work. These relationships hold at both the between and within person level: individual coaches’ general mindfulness levels relate to their wellbeing, as do day to day variations in mindfulness. Findings from the three studies have important practical implications. Mindfulness can be developed and enhanced through training and practice. For coaches who are challenged by the demands and pressures of their job, or for the organisations who employ or support those coaches, focusing on building mindfulness could be a powerful strategy for improving and maintaining wellbeing.