ImportanceSnoring is central to sleep-disordered breathing (SDB), which arises from nocturnal upper airway resistance. Habitual snoring is associated with cognitive and behavioral problems in young children, but less is known about these associations in adolescents.ObjectiveTo assess the longitudinal associations of snoring with cognition and problem behaviors among adolescents.Design, Setting, and ParticipantsThis cohort study was a secondary analysis of the Adolescent Brain Cognitive Development (ABCD) Study dataset (release 5.0), which enrolled 11 875 children and a parent or caregiver from June 1, 2016, to October 15, 2018, at 21 participating US research institutions and followed-up for 5 years. The analysis was performed between December 2023 and April 2024.ExposuresParent-reported snoring categorized as none, nonhabitual (<3 nights/week), and habitual (≥3 times/week).Main Outcomes and MeasuresCognition was assessed using 5 measures from the National Institutes of Health Toolbox (NIH-TB), and caregiver-reported problem behaviors were assessed using the Child Behavior Checklist (CBCL), including Total Problems, Internalizing Problems, and Externalizing Problems. Longitudinal associations of snoring with these assessment measures were analyzed using linear mixed-effects models stratified by obesity. Model fits were assessed after including the fixed-effects of age, sex at birth, race, family income, follow-up time, visit type, and the random-effects of site and identification number.ResultsThe study included data from 11 862 children at year 1 (mean age, 119.0 months [95% CI, 118.8 to 119.1 months]; 6164 male [52.2%]) and 11 198, 10 870, 10 064, and 4668 children at years 2 to 5, respectively. The proportion of habitual snorers decreased from 811 participants (6.8%) in year 1 to 150 participants (3.2%) in year 5. Snoring was not associated with any of the NIH-TB scores. A statistically significant association of snoring was identified with all CBCL scales. The largest-magnitude association was of snoring with the CBCL Total Problems scale among adolescents with obesity (β = 3.18; 95% CI, 2.59-3.77).Conclusions and RelevanceIn this cohort study analyzing associations of snoring with cognitive test scores and problem behaviors based on the ABCD dataset, the prevalence of snoring declined over time; snoring in adolescents was associated with problem behaviors but not cognitive deficits. These findings may aid shared decision-making regarding treatment options such as adenotonsillectomy for adolescents with SDB.