Self-concept clarity (SCC) is defined as “the extent to which the contents of an individual’s self-concept (e.g., perceived personal attributes) are clearly and confidently defined, internally consistent, and temporally stable,” (Campbell et al., 1996, p.141). This thesis aimed to identify and examine the relationships between SCC and traumatic events and how SCC might play a role in influencing outcomes for trauma survivors. Chapter one encompasses a systematic literature review examining associations between SCC and traumas. Systematic searches were conducted in five databases (PsycInfo, PsycArticles, PUBMED, CINAHL and Web of Science). Sixteen eligible studies were included, exploring SCC alongside childhood trauma, bereavement, sexual assault, birth trauma and terrorism. There was consistent evidence linking SCC with childhood adversity and specific traumatic events during adulthood. Chapter two describes an empirical study that aimed to explore whether SCC mediated the relationship between trauma during childhood or adulthood and post-traumatic stress disorder (PTSD) symptoms. A clinical sample of primary care mental health service users was recruited via email to participate in an online survey capturing information about demographic, SCC, PTSD symptoms and traumatic experiences (the nature of the trauma, the age at which it happened and whether it was repeated). Analyses revealed that SCC played a mediating role between trauma age and PTSD outcomes. There was a stronger association between lower SCC and higher PTSD outcomes in those who had been traumatised during childhood compared those who had experienced trauma exclusively in adulthood. Clinical implications, limitations and future directions for research are discussed. Chapter three provides a critical appraisal of the two previous chapters, including an overview of the findings, critical reflections and the strengths and limitations of the project.