It has been well established that self-harm is a key healthcare issue facing young people (Health and Social Information Centre, 2015). Consequently, many self-harmers preferentially seek support from friends (Evans, Hawton, & Rodham, 2005). Despite their unique position, friends’ experiences have been marginalised. Historically, friends have only been considered when they feature in the lives of the person who self-harms, when they are identified as “gate-keepers” to self-harming young people (Klingman & Hochdorf, 1993, p. 123), or when they themselves go on to self-harm (e.g. Hawton, Rodham, Evans, & Weatherall, 2002). Bearing in mind the friends’ unique, yet highly vulnerable status, there is a notable lack of research exploring how friends come to understand their experiences, and the subsequent impact this has on their friendships with the self-harmer. Through this qualitatively approached thesis I aimed to explore how the impact of self-harm on friendship is understood. Data was collected through a series of interviews and focus groups with friends of self-harmers, and those who supported them. Using a qualitative methodology, I conducted three studies. In Study One, I explored how counsellors made sense of the impact of self-harm on friendship. Studies Two and Three focussed on how friends, whilst maintaining a friendship with a self-harmer, came to understand themselves, their friendship with the self-harmer, and their relationships with others. The results indicated that friends struggled to integrate self-harm into their friendships and their understanding of themselves, took on excessive responsibility for the self-harmer, and felt constrained by secret-keeping. Additionally, as the friends in Study Three felt that information available to them was either absent, or lacking, I developed a prototype support tool tailored specifically to the needs of the friends.