Adolescents and young adults (AYA) with inflammatory bowel diseases (IBD) are at risk for nonadherence. This study described AYA adherence barriers and correlates of barriers. 77 AYA-parent dyads completed measures of adherence barriers. Disease frustration barriers were the most commonly endorsed barriers among AYA and parents. Females, those with Crohn’s disease, and those with active disease displayed higher levels of selected variables. AYA with IBD experience unique adherence barriers. Routine screening for barriers, especially disease frustration barriers, is warranted. Adherence-promotion interventions should be tailored to AYA’s unique experience and should emphasize disease and regimen frustration.