BackgroundExternalised mess-making processes create a distinction between art psychotherapy and other psychotherapy modalities, offering a unique window into the inner world of clients. Currently there is a limited amount of evidence on the role of mess in art psychotherapy, largely focusing on children. This study sets out to explore the role of mess-making in art psychotherapy from a broader client perspective and to investigate how art psychotherapists can work alongside mess-making to best support clients.AimsThe study has three broad aims - to identify themes that enhance understanding of the therapeutic value of mess-making in art psychotherapy, examine key barriers and enablers of working with mess, and explore practice implications for art psychotherapists.MethodsA qualitative approach was adopted utilising semi-structured interviews with 7 UK-based qualified art psychotherapists, representative of a range of settings and spanning diverse client populations. Reflexive thematic analysis was used to analyse the data.ResultsThe analysis resulted in 4 core themes - mess is welcome here, mess as a communication tool, the unfolding journey of mess, and the active therapist.ConclusionThe findings enhance current understanding of the therapeutic value of mess, confirming its value for a range of client populations The study also reveals key stages of mess-making in art psychotherapy within the therapeutic journey.Implications for practice/policy/future researchThis study highlights some of the challenges of working with mess, the importance of tailored approaches to support mess-making for clients, and also the need for a broader awareness of these important processes.Plain-language summaryArt psychotherapy offers clients a unique opportunity to explore thoughts and feelings through mess-making processes but, to date, the research into mess-making in therapy focuses largely on children. This study sets out to explore the functions and benefits of mess-making in therapy for all clients, regardless of age and stage. Using interviews with UK-based registered art psychotherapists in a range of clinical settings, the research explores the benefits of mess-making for a wide range of clients, and examines the stages of mess-making that unfold across the therapy journey. Findings indicate the importance of tailoring support for clients in mess-making, as well as a need to generate a broader awareness of the benefits of mess-making within clinical settings so that it can be understood and supported appropriately.