Background: Accurate and complete medication histories are not always obtained in clinical practice., Objective: This qualitative research study was undertaken to explore the barriers to and facilitators of obtaining accurate medication histories., Methods: Individual interviews, based on a structured interview guide, were conducted with 25 patients from both inpatient and ambulatory care clinic settings. Focus groups, based on a semistructured interview guide, were conducted with pharmacists, medical residents, and nurses. Transcribed data were analyzed by forming coded units and assessing these units for emerging themes., Results: Major themes that emerged from the patient interviews included patient ownership of health and medication knowledge (with knowledge of medications and their side effects and how to take medications being seen as important), patient-specific strategies to improve medication histories (e.g., use of regularly updated medication lists), and suggestions for system-level facilitators to improve medication histories (e.g., centralized databases of medication histories, increased patient education regarding the use and purpose of medications). Major themes also emerged from focus groups with health care professionals, including shared responsibility for medication history-taking among all 3 health care professions, perceptions about the barriers to medication history-taking (including patients not knowing their medications and not bringing their medication lists), and suggestions to improve medication histories (e.g., educating patients to bring medication vials to hospital admissions and appointments, using a centralized computer database for medication histories)., Conclusions: Key recommendations resulting from this study include using standardized documentation techniques for medication histories, recording of medication history information in centralized electronic databases, educating patients to bring medications to every health care visit, and establishing criteria for pharmacist referral for cases involving complex medication histories.