Introduction to the Special Issue on Adolescent and Young Adult Health: Why We Care, How Far We Have Come, and Where We Are Going.

This special issue on adolescent and young adult (AYA) health comprises 15 original articles. The special issue recognizes the importance of AYA-focused research, highlights unique issues across the AYA period, and showcases cutting-edge research focused on AYAs. We describe the rationale for focusing on the AYA population, themes of the special issue, and future directions. [ABSTRACT FROM AUTHOR]