Wellbeing research has recently gathered impetus largely due to the emergence of positive psychology. Researchers and practitioners are now exploring the science of positive subjective experiences, positive traits, positive states, aspects of human strengths and quality of life. Despite work and family deemed to be two of the most important domains of life, work and family wellbeing has received little attention in the positive psychology literature. Therefore, this thesis expands the landscape of the wellbeing literature by focusing on the work-family interface, the roles of resilience and work-life balance in achieving job and family satisfaction and psychological health. Specifically, my research sought to examine cross-sectional and longitudinally, the mediation effects of resilience and work-life balance between work-family conflict (time, strain and behaviour), work-family enrichment (development, affect and capital/efficiency) and a broad range of wellbeing outcomes (job satisfaction, family satisfaction, anxiety/depression, and social dysfunction) with health professionals. Health professionals in New Zealand are consistently exposed to psycho-social risk factors such as heavy workloads, irregular work schedules, and long hours of work. In addition, global demand for health professionals is at an all time high, with New Zealand-trained staff looking overseas for employment. The work-family literature is plentiful in studies exploring work-family conflict with a multitude of outcomes (e. g. job satisfaction, psychological and physical health, organisational commitment, turnover and turnover intentions). However, there are several gaps in the literature. Firstly, the work-family interface where little attention has been given to exploring a) the family to work directionality and the three forms of conflict (time-based, strain-based, and behaviour-based) is limited. In addition, a few studies have provided a holistic perspective in analysing the positive of the work-family interface in the form of (b) work-family enrichment (development, affect and capital/efficiency) and the impact on their experiences of life with health professionals in New Zealand. Furthermore, most studies that have utilized resilience have done so with adolescents in family settings with little emphasis placed on (c) exploring employee resilience in the workplace and its role towards wellbeing. Finally, the literature often fails to categorize and (d) test work-life balance as a subjective measure. Consequently, the present thesis examines all these issues. This research involved a two-wave panel design with a 10-12 month time-lag. Self reports on the eighteen latent variables were obtained from 1,598 health professionals at Time 1 and 296 at Time 2, employed by two District Health Boards (Waikato District Health Board and Lakes District Health Board) and one health provider (Toi Te Ora-Public Health) in New Zealand. SPSS was used to undertake the correlation analyses and structural equation modelling (SEM) to assess the mediation hypotheses. The Time 1 cross-sectional results provided evidence for a mediating effect of resilience with work→family conflict (time and strain), family→work conflict (strain and behaviour), work→family enrichment (capital), family→work enrichment (development and efficiency) with all four wellbeing variables (job and family satisfaction, anxiety/depression and social dysfunction) and work-life balance. However, at Time 2 the results were less frequent, with mediation support for resilience between work→family conflict (time, and behaviour), and three of the wellbeing variables (family satisfaction, anxiety/depression and social dysfunction) and work-life balance. In addition at Time 1, work-life balance mediated the relationships between work→family conflict (time and strain), family→work conflict (time) and work→family enrichment (affect) with the wellbeing variables (job satisfaction, family satisfaction, and anxiety/depression). At Time 2, work-life balance mediated the relationship between work→family conflict (time and strain) with family satisfaction, and social dysfunction. The longitudinal analyses confirmed that work-life balance mediated the relationship between work→family conflict (time) with job satisfaction, family satisfaction, anxiety/depression and social dysfunction, whereas, no longitudinal support was found for mediation effects of resilience. This research makes several contributions, including that in order to improve levels of wellbeing, health professionals need to continue to alleviate work-family conflict. This research showed the strength of conflict on employee wellbeing and that resilience and work-life balance may provide mechanisms that may improve such wellbeing outcomes. The work-life balance longitudinal mediation results have implications for developing time based strategies are needed between work and family that aim in reducing ‘conflict’ to increase the health professionals’ wellbeing. Although there was considerable support for resilience as a mediator at Time 1 (35 significant paths out of a potential 60 mediation routes tested) limited findings were evident at Time 2 (8 mediation paths were significant out of a possible 60 routes tested) and no longitudinal effects were found. This may indicate that resilience as mediator is not stable over time and therefore may be more state-like rather than a stable trait. Further research is needed to investigate resilience and work-life balance and their role within a wellbeing model to advance theory and practice. Overall, the thesis shows the value of testing fuller models of conflict and enrichment (with all dimensions) towards wellbeing outcomes, and the importance of accounting for resilience and work-life balance in these models.