Aims and method To establish an initial conceptualisation of how psychiatrists understand and use formulation within adult psychiatry practice. Twelve psychiatrists took part in semi-structured interviews. Transcripts were analysed using a constructivist grounded theory methodology.Results Formulation was conceptualised as an addition to diagnosis, triggered by risk, complexity and a need for an enhanced understanding. Participants valued collaborative formulation with psychologists. Multiple contextual factors were perceived to either facilitate or inhibit the process. Barriers to formulation led to a disjointed way of working.Clinical implications Findings contribute to an understanding of formulation within psychiatry training and practice.