With increasing interest in studies evaluating treatment outcome in children with attention deficit hyperactivity disorder (ADHD), there is a need for treatment-sensitive instruments that are feasible, yield valid and reliable scores, and measure outcome in a “time-locked” and “situation- and symptom-specific” manner. These instruments are needed to evaluate the outcome for which the treatment is targeted at specific settings (e.g., school), specific times of day (e.g., the late afternoon or early evening medication dose), and specific symptoms (e.g., hyperactivity). The Telephone Interview Probe (TIP) was developed to meet this need for outcome research with children with ADHD. The present study evaluated the feasibility, reliability, validity, and treatment sensitivity of scores on the TIP scales (Inattention, Hyperactivity-Impulsivity, Oppositional Behavior, and Problem Situation). Psychometric properties of the TIP were evaluated using classical test theory, as well as generalizability theory. The TIP proved to possess all the attributes required for use in large-scale treatment studies.