Objectives To examine the issue of accurate adherence assessment and illustrate methodologies for correcting parent-reported medication adherence. Methods 40 children with inflammatory bowel disease provided medication adherence data using electronic monitoring. Parents provided subjective reports of medication adherence. Receiver operating characteristic analyses were used to examine the detection of non-adherence at several adherence cut-points. 2 methods for empirically deriving a correction factor for subjectively reported adherence were applied. Results Although parent-report and EM adherence were significantly correlated, parent-reported adherence was significantly higher than EM adherence. A 90% cut-point provided the highest sensitivity and specificity. Both correction factors reliably adjusted parent-reported adherence based on EM adherence. Conclusions Application of an empirically derived correction factor for parent-reported adherence using methodologies, such as those illustrated in the current study, could yield more accurate adherence assessment. Obtaining more accurate adherence assessments based on parent-report will have implications for self-management interventions, clinician prescribing behavior, and medication safety.