We were asked by the editors to review “A Checklist for Retrospective Database Studies” by Brooks et al. that appears in this issue and to suggest additional guidance for manuscript reviewers and researchers in this field. Our review was a joyful task, because the ISPOR committee that authored the Checklist performed an excellent service in the daunting area of longitudinal database research. A guide such as this one would have been useful in the mid-1980s, when epidemiologists and economists began using claims databases in studies of drug safety and outcomes research. Unfortunately, those early researchers had to find their way by trial and error and by building the research tools carefully, validating against primary records at each step of the process. This ISPOR guidance builds on that groundbreaking work and adds lessons from the unique challenges encountered in assessing the economic impact of therapeutics.