In the recent past, we have seen a profusion of scientific articles with observations based on cohorts that were derived from administrative health care databases (AHDs), including the Pediatric Health Information System and the Kids’ Inpatient Database, together accounting for 7977 peer reviewed articles since 2000. However, we lack criteria for appraising the validity of the cohorts that investigators derive from the base population. A concerted effort by investigators, editors, and reviewers is needed to qualify and improve this key aspect of study design.