Youth in underserved communities lack access to consistent sources of high-quality health care. School-based health centers (SBHCs) address this challenge through the provision of primary care, mental health care, and other health services in schools. This article describes the current status of SBHCs nationally, including changes over the past twenty years. Data were collected through the School-Based Health Alliance's National School-Based Health Care Census. The number of SBHCs doubled from 1,135 in 1998-99 to 2,584 in 2016-17. During this time they adapted to the changing health care landscape and community needs. Sponsorship shifted predominantly to federally qualified health centers, and SBHCs provided access to primary care and, often, to mental, oral, and other health services to 10,629 schools and over 6.3 million students. SBHCs have grown steadily since 1998, and recent expansion through federally qualified health centers and telehealth technology forecasts even greater growth, innovation, and access for underserved communities.