This book presents a comprehensive examination of the evolving landscape of Medicare and Medicare Advantage. It explores key challenges and opportunities in enrollment, behavioral health coverage, and the intersection of healthcare and housing for vulnerable populations. Chapter 1 outlines current enrollment trends and policy issues, offering insight into how federal programs can better meet the needs of an aging population. Chapter 2 analyzes cost-sharing practices in behavioral health services—highlighting disparities and gaps in access to mental health care. Chapter 3 investigates Medicare Advantage coverage rates among individuals receiving federal housing assistance, underscoring issues of healthcare equity and social determinants of health.