Adolescents with attention-deficit/hyperactivity disorder (ADHD) experience academic difficulties, but there are limitations to current methods of measuring these problems. The parent-rated Adolescent Academic Problems Checklist (AAPC) is a particularly promising measure, as the items were derived from concerns of parents and teachers of adolescents with ADHD and the scale demonstrates good concurrent validity and treatment sensitivity (Sibley et al. in School Psychology Quarterly, 29(4), 422, 2014; Sibley et al. Journal of Consulting and Clinical Psychology, 84(8), 699, 2016b). Because parents do not observe some academic behaviors queried on the AAPC, they may provide inaccurate responses to some items, leading to measurement error. In the current study, we sought to (1) determine the extent to which parents of adolescents with ADHD possess knowledge of the academic behaviors assessed on the AAPC, (2) determine if the scale maintains the two-factor structure (academic skills and disruptive behavior) and continues to relate to indicators of academic functioning after removing items associated with low parent knowledge, and (3) validate findings with the revised scale in a separate sample of adolescents with ADHD. Results identified five items for which the majority of parents reported little to no knowledge. When removing items with low parental knowledge, the AAPC’s model fit was maintained and the two-factor model remained a better fit than the one-factor model. The relationships between the revised subscales and measures of academic functioning remained significant and largely equivalent to the original version. The revised model demonstrated similar fit in the second sample and was also related to indicators of academic functioning. Implications for clinical practice are discussed.