Understanding deviations in care can identify opportunities to improve care delivery and patient safety. This study assessed the incidence and nature of patient- and clinician-reported deviations from optimal care (“non-routine events” or NRE) during ambulatory surgery. The most common type of clinician-reported NRE was process deficiencies, while failures in communication between clinicians and patients or family members was the most common type of patient-reported NRE. Understanding patient perspectives on care deviations can identify opportunities for process improvements and more patient-centered care.