Given a trend towards higher burnup power reactor fuel, the IAEA began an active programme in burnup credit (BUC) with major meetings in 1997 (IAEA TECDOC Series No. 1013), 2000 (IAEA TECDOC Series No. 1241) and 2002 (IAEA TECDOC Series No. 1378) exploring worldwide interest in using BUC in spent fuel management systems. This publication contains the proceedings of the IAEA’s 4th major BUC meeting, held in London. Sixty participants from 18 countries addressed calculation methodology, validation and criticality, safety criteria, procedural compliance with safety criteria, benefits of BUC applications, and regulatory aspects in BUC. This meeting encouraged the IAEA to continue its activities on burnup credit including dissemination of related information, given the number of Member States having to deal with increased spent fuel quantities and extended durations. A 5th major meeting on burnup credit is planned for 2008.