Medicare Advantage (MA) enrollment growth could make it difficult for MA plans to maintain their track record of limiting discretionary utilization while delivering higher-quality care than traditional Medicare. We compared quality and utilization measures in Medicare Advantage and traditional Medicare in 2010 and 2017. Clinical quality performance was higher in MA health maintenance organizations (HMOs) and preferred provider organizations (PPOs) than in traditional Medicare for almost all measures in both years. MA HMOs outperformed traditional Medicare on all measures in 2017. MA HMOs' performance on nearly all seven patient-reported quality measures improved, and MA HMOs outperformed traditional Medicare on five of those measures in 2017. MA PPOs performed the same as or better than traditional Medicare on all but one patient-reported quality measure in 2010 and 2017. The number of emergency department visits was 30 percent lower, the number of elective hip and knee replacements was approximately 10 percent lower, and the number of back surgeries was almost 30 percent lower in MA HMOs than in traditional Medicare in 2017. Utilization trends were similar in MA PPOs, but differences from traditional Medicare were narrower. Despite increased enrollment, overall utilization remains lower in Medicare Advantage than in traditional Medicare, whereas quality performance is the same or higher.