Audit is an important tool for quality improvement. The collection of data on clinical performance against evidence-based and clinically relevant standards, which are considered by clinicians to be realistic in routine practice, can usefully prompt reflective practice and the implementation of change. Evidence of participation in clinical audit is required to achieve intended learning outcomes for trainees in psychiatry and revalidation for those who are members of the Royal College of Psychiatrists. This article addresses some of the practical steps involved in conducting an audit project, and, to illustrate key points, draws on lessons learnt from a national, audit-based, quality improvement programme of lithium prescribing and monitoring conducted through the Prescribing Observatory for Mental Health.