Sustainability appraisal involves the systematic identification and evaluation of the potential impacts on sustainability concerns of a policy, plan, programme or project, in order that its performance in relation to sustainable development may be improved. UK government guidance currently requires regional planning guidance (RPG) and regional economic strategies (RESs) prepared for each English region to undergo a sustainability appraisal. To this end, the Department of the Environment, Transport and the Regions in August 1999 published its Proposals for a Good Practice Guide on the Sustainability Appraisal of Regional Planning Guidance (the proposed guide) that were also potentially applicable to RESs. RPG and RES preparation was under way at this time and it is therefore unreasonable to expect the recommendations of the proposed guide to have been met in full, since these are based on the premise that appraisal is initiated at the same time as the strategy development process. Nevertheless, it is important to benchmark the performance of the accompanying appraisals in order that any problems, deficiencies or examples of best practice may be identified and used to inform the preparation of future appraisals. This paper presents the findings of a review of reports documenting the sustainability appraisal process as it applied to RPG for six English regions and RESs for seven regions. The aim was to address the extent to which the appraisals conformed to the procedural and methodological recommendations detailed in the proposed guide. The results of the review suggest that, although some aspects of the proposed guide were followed, certain fundamental elements were lacking, thus lessening the effectiveness of the appraisals in influencing strategy performance. Possible reasons for these failures are discussed and recommendations for future improvements put forward.