The Adolescent Brain Cognitive Development (ABCD) Study is the largest, long-term study of brain development and child and adolescent health that has ever been conducted in the United States. The ABCD Research Consortium is supported by the National Institutes of Health and includes a central coordinating center, a data analysis and informatics core, and 21 research sites across the country. This special issue of Health Psychology presents some important findings on adolescent health behavior that have recently emerged from the ABCD Study (PsycInfo Database Record (c) 2023 APA, all rights reserved).