Background: The body of evidence surrounding adult and elderly carer outcomes is well established, however fewer studies have been conducted with young carers (those < 18 years with caring responsibilities). Given the negative outcomes associated with caregiving, the experience can be conceptualised as a risk factor for health, requiring protective factors to promote adaptation. Positive outcomes have also been associated with caregiving, suggesting that protective factors and resilience may be inherent in the caregiving role. Protective resilience factors have been identified in adult and elderly carers, and are typically theorised within the three levels of the socioecological model of resilience (individual, community and society). Biopsychosocial research, from a resiliency perspective is necessary to identify the factors contributing to, and pathways towards, resilience, in order to promote positive outcomes in young carers. Aims: The overall aim of the current research programme was to explore the mechanisms underlying psychophysiological resilience in young carers. Specifically, the aim was to identify protective factors which contribute to perceived stress, resilience and physiological outcomes in this population. Method: A mixed methods, sequential design was used across three studies. First, a systematic review was conducted following Prisma guidelines. Second, qualitative photo elicitation interviews were carried out with young carers and analysed using thematic analysis. Finally, a quantitative study was conducted using questionnaires to measure psychosocial factors, and hair samples to assess hair cortisol concentration in young carers and an age-gender matched noncarer control group; data were analysed using statistical techniques including correlation, t-tests, regression and moderation. Summary of findings: The systematic review identified that coping, social support, stress appraisal and carer activities contributed to carer adjustment and outcomes. Evidence was found for both the transactional model of stress and the socioecological model of resilience. The second study identified 11 factors within the three levels of the socioeconomic model of resilience. Individual factors included pre-empting challenges and planning ahead, cognitive strategies, emotional strategies and seeking solitude. Community factors included family support, friendships, and pets and inanimate objects. Societal factors included professional support, access to carer activities and community, being outdoors and disability aids. The findings of this study provided further support for the socioecological model and also identified potential protective factors in a population of young carers. The final study found that young carers reported significantly greater perceived stress than non-carers but did not demonstrate higher hair cortisol concentration. A negative association was found between perceived stress and resilience in young carers and non-carers, and a positive association between perceived stress and hair cortisol concentration was found in young carers. No significant associations were found between resilience and hair cortisol concentration. A relationship was found between perceived stress and benefit finding in the young carer group and no significant relationships were found between benefit finding and hair cortisol concentration in either group. Mediation analyses of benefit finding and resilience as mediators of perceived stress and hair cortisol were not run due to requirements for this analysis not being met. In addition to resilience, caregiver status and avoidant coping contributed to perceived stress. As well as perceived stress, family support, social support and benefit finding contributed to resilience. There were no significant contributory factors identified for variance in hair cortisol, social support did not act as a moderator of perceived stress on hair cortisol. Conclusions: This programme of research identified a number of potential protective resilience factors in a population of young carers, contributing to an area of literature previously unexplored. The findings of this research support the transactional model of stress and coping, and offer substantial evidence for the relevance and applicability of the socioeconomic model of resilience in young carers. The use of physiological assessment in the form of hair cortisol concentration adds to the general psychoneuroendocrine literature and further develops the stance of immunosenescence in carers. The research makes methodological contributions and provides a basis for both future research with young carers and the development of stress resilience interventions, whereby the factors identified in this work can be harnessed to promote positive outcomes.