Empirical work has examined the utility of using person-centered statistical approaches emphasizing traits to parsing attention deficit/hyperactivity disorder (ADHD) heterogeneity in preschool and school-age children. However, trait-based profiles have not yet been examined in other age ranges, specifically adolescence and young adulthood. Therefore, the goal of the present study is to examine trait-based profiles in adolescents and young adults with ADHD to evaluate their similarity with trait-based profiles in preschoolers and children with ADHD and through comparison with external correlates (e.g., comorbidity). One hundred eighty-two adolescents and 287 young adults completed measures of ADHD symptoms, personality and temperament traits, and comorbid internalizing and externalizing problems. Latent profile analysis suggested at least 3 consistent trait-based profiles related to ADHD within adolescents and young adults: low extraversion, high extraversion, and high neuroticism. These profiles were largely similar to those found in preschool and middle childhood and demonstrated similar comorbidity patterns, namely, the low-extraversion profile exhibited higher internalizing problems, the high-extraversion profile exhibited higher externalizing problems, and the small high-neuroticism profile exhibited descriptively higher levels of all comorbid problems. Such profiles may have utility for personalization of intervention based on trait profiles and comorbidity patterns, as well as-more speculatively-possible prognostic utility.