Medicare spending growth has slowed markedly over the last 20 years, defying projections despite a growing beneficiary population and expansion of the costlier Medicare Advantage program. Demographic, policy, and economic factors contributed to the spending growth slowdown. Key drivers include low payment rate increases—particularly following passage of the Affordable Care Act and sequestration policies—modest demographic shifts, and the evolving role of financial incentives and medical technology. The orientation toward value-based care played a role, though precise impacts of broad policies are difficult to quantify. While spending moderation is viewed as a success, it may mask trade-offs in access, quality, and service adequacy, especially for vulnerable populations facing unmet needs. We explore future spending projections and highlight the importance of balancing cost control with improving Medicare’s capacity to serve high-need beneficiaries. Research insights are critical for shaping Medicare policy that is financially sustainable and responsive to beneficiaries’ evolving needs.