Background: Recent research has indicated that school-based humanistic counselling (SBHC) is effective for young people in reducing psychological distress and facilitating achievement of personal goals. However, the processes by which this form of counselling brings about change are not yet understood. Aim: This study aims to clarify the dynamic processes of change that young people go through when they attend SBHC, in order inform school counselling practice, training and further research. Method: This is a qualitative interview study with 14 participants who had recently completed between two and nine sessions of SBHC as part of a randomised controlled trial (RCT). Interviews were transcribed and analysed using a grounded theory approach resulting in the development of five change process models. Results: Multiple change processes were evident for individual clients; and were labelled relief, increasing self-worth, developing insight, enhancing coping strategies and improving relational skills. Implications: The data indicate that multiple pathways of change are possible, and that change processes associated with different theories of personality change are not mutually exclusive. The study is limited by a small, selective sample and low testimonial validity, and further qualitative research is needed to understand change processes in SBHC more fully.