This article describes the development of assessment criteria for specific aspects of examination answers and coursework essays in psychology. The criteria specified the standards expected for seven aspects of students' work: addressing the question, covering the area, understanding the material, evaluating the material, developing arguments, structure and organisation, and clarity in presentation. The criteria were designed to promote student learning, increase the reliability of marking, facilitate research on marking, and promote reflective practice among markers. Student feedback indicated that, despite being published in course materials, the impact of the criteria on students was much less than it could be, but the criteria supported other initiatives to promote student learning, including more structured feedback to students on coursework essays, and generic skills teaching on essay writing. The criteria were used in research to analyse the judgments made by markers of examination answers. That research revealed substantial individual differences among markers and more systematic differences between first and second markers. Some staff had reservations about specifying the assessment criteria in such detail, but the criteria provided a stimulus for staff reflection on the process of marking and agreeing marks. The development of the criteria opened up a number of avenues for further work on student learning and assessment and for further research on the psychology of marking. (Contains 3 tables.)