Objective: The current study reports functional outcomes from a multi-site randomized trial of a cognitive-behavioral treatment program for college students diagnosed with ADHD. Methods: A sample of emerging adults (N = 250; ages 18 to 30) currently attending college were comprehensively evaluated and diagnosed with ADHD (M age = 19.7; 66% female, 6.8% Latino, 66.3% Caucasian). Participants were randomized to either a two-semester intervention (Accessing Campus Connections and Empowering Student Success (ACCESS)) or a delayed treatment condition. Participants were assessed with measures of academic, daily life, and relationship functioning prior to treatment, at the end of the first semester, and after the second semester of treatment. Results: Multi-group latent growth curve models revealed moderate effect size improvements on self-report measures of study skills and strategies, as well as on self-report measures of time management, daily functioning, and overall well-being for participants in ACCESS. Importantly, treatment effects were maintained or increased in some cases from the end of the first semester to the end of the second semester. Improvements in self-reported interpersonal functioning were not significantly different across condition and neither condition demonstrated significant change over time in educational record outcomes (GPA and number of credits earned). Conclusions: ACCESS appears to promote improvements in self-reported general well-being and functioning, time management, and study skills and strategies. However, improvements in interpersonal relationships and objective academic outcomes such as GPA were not observed. Clinical implications and future directions for treating ADHD on university and college campuses are discussed. [This is the online version of an article published in "Journal of Clinical Child & Adolescent Psychology."]