This paper gives an overview of the methods of moderation, or quality assurance and quality control, as they may be more widely known, that are used to enhance the quality of student assessment. The discussion is based on the educational systems of the United Kingdom but is applicable to assessment in other countries. Quality in assessment is seen as the provision of information of the highest validity and optimum reliability suited to a particular purpose and context. Moderation procedures fall broadly into those concerned with adjustment of the outcome of the assessment to improve fairness (quality control) and those concerned with arriving at fair assessments (quality assurance). Approaches to quality control are: (1) the use of reference or scaling tests for statistical moderation; (2) the inspection of samples by post (e.g., sending a sample of work to an outside organization for an award); (3) the inspection by visiting moderators; (4) external examination; (5) teacher-requested moderation; and (6) group and consensus moderation of internal assessment. Approaches to quality assurance, which are usually made before the assessment, include definition of criteria, providing examples, approving entities carrying out assessment, visits of moderators, and group moderation. The quality of teacher assessments can be enhanced through moderation procedures that support professional development. (Contains 18 references.) (SLD)