"This Methodology Paper summarizes the process, a modified Delphi approach, used to develop a specific checklist for the quality appraisal of case series studies. This work was supplemented with a review of other published checklists and an initial pilot test of the newly developed quality appraisal checklist. Researchers at the Institute of Health Economics with researchers from two other Health Technology Assessment agencies in Australia and Spain were actively engaged throughout the Delphi process"--Back cover.