Advanced access is an outpatient scheduling technique that aims to provide same-day appointment access. It is designed to reduce the time patients must wait for a scheduled appointment and to improve continuity of care by matching daily appointment supply and demand. Factors that make it difficult to sustain initial success in achieving supply-demand balance include different practice styles of doctors, differences in panel compositions and patient preferences, and time-varying demand patterns. This article proposes several performance measures that can help clinic directors monitor and evaluate their advanced access implementation. We also discuss strategies for sustaining advanced access in the long run.