Objective: To examine the relationship between behavioral functioning specific to attention and conduct problems and prescription medication adherence in youth with Inflammatory Bowel Disease (IBD) and to examine the potential mediational role of perceived barriers to medication adherence. Low rates of medication adherence are a documented problem for youth with IBD with the potential for negative health consequences. There is a need to identify potentially malleable factors associated with poor adherence such as behavioral functioning and barriers so that treatment interventions can be developed. Methods: Eighty-five adolescents with IBD and their parents completed measures of adherence, attention and conduct problems, and barriers to adherence while attending a regularly scheduled clinic appointment. To examine the proposed mediation models, the traditional Baron & Kenny (1986) approach in combination with formally testing the indirect effect using procedures outlined by Preacher & Hayes (2004) was used. Results: Attention and conduct problems were negatively associated with adherence. Analyses supported the mediational role of perceived barriers in the relationship between behavioral problems and adherence. Conclusions: Results indicate that attention and conduct problems are risk factors for lower adherence in youth with IBD and that barriers may account for the relationship.