This study possessed 2 aims: (a) to develop and validate a clinician-friendly measure of academic problem behavior that is relevant to the assessment of adolescents with attention deficit/hyperactivity disorder (ADHD) and (b) to better understand the cross-situational expression of academic problem behaviors displayed by these youth. Within a sample of 324 adolescents with the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision diagnosed ADHD (age M = 13.07, SD = 1.47), parent, teacher, and adolescent self-report versions of the Adolescent Academic Problems Checklist (AAPC) were administered and compared. Item prevalence rates, factorial validity, interrater agreement, internal consistency, and concurrent validity were evaluated. Findings indicated the value of the parent and teacher AAPC as a psychometrically valid measure of academic problems in adolescents with ADHD. Parents and teachers offered unique perspectives on the academic functioning of adolescents with ADHD, indicating the complementary roles of these informants in the assessment process. According to parent and teacher reports, adolescents with ADHD displayed problematic academic behaviors in multiple daily tasks, with time management and planning deficits appearing most pervasive. Adolescents with ADHD display heterogeneous academic problems that warrant detailed assessment prior to treatment. As a result, the AAPC may be a useful tool for clinicians and school staff conducting targeted assessments with these youth.