Approaching Retention within the ABCD Study

•Retention is critical in longitudinal, multi-site studies of adolescents.•Differential retention can impact generalizability of study outcomes.•We review efforts utilized by the ABCD study staff to ensure high retention. Retention efforts are critical to maintain relationships with research participants over time. This is especially important for the Adolescent Brain Cognitive Development (ABCD) study, where families are asked to stay engaged with the study throughout the course of 10 years. This high-degree of involvement is essential to longitudinally track child and adolescent development. At a minimum, we will connect with families every 6 months by telephone, and every year in person, with closer contact with the youth directly as they transition into adolescence. Differential retention, when related to non-random issues pertaining to demographic or risk features, can negatively impact the generalizability of study outcomes. Thus, to ensure high rates of retention for all participants, the ABCD study employs a number of efforts to support youth and families. This overview details the framework and concrete steps for retention.