By analysing research into links between low psychological wellbeing and sexual risk-taking behaviours that occur in men who have sex with men (MSM), this book demonstrates what impact social and psychological interventions could have on MSM at risk of poor sexual outcomes. At the heart of the book is Identity Process Theory, co-developed by the author, a social psychological theory of identity construction, threat and coping. The book considers the emerging debates in MSM's health, such as the use of Grindr and 'chemsex', and also explores the socio-structural factors, such as homophobia and stigma, that threaten the self-identity of MSM. The book offers principles and techniques from this theory that can be used as an effective intervention and therapeutic model with MSM to build more positive identities and reduce sexual risk-taking.