jats:p To illuminate individual differences in the development of attention-deficit hyperactivity disorder (ADHD) symptoms in the general population, psychometric measures are needed that can capture general population-level symptom variation reliably, validly, and comparably from childhood through to the transition to adulthood. The ADHD subscale of the Social Behavior Questionnaire (SBQ-ADHD) provides a candidate for a measure that can meet this need. We thus evaluate the psychometric properties of the SBQ-ADHD as administered in adulthood (ages 20 and 24) to a large normative sample, as well as the cross-informant (parent-teacher-self-reports) and developmental (ages 7–24) measurement invariance of a core SBQ-ADHD item set. Results support score internal consistency reliability, gender measurement invariance, and criterion validity. Scores from the core item set showed some evidence of non-invariance, providing insights into how ADHD symptoms may manifest and/or be perceived differently by different informants/in different contexts and at different ages. Our findings overall support the use of the SBQ-ADHD items for developmental studies of ADHD symptoms from childhood to adulthood. </jats:p>