This chapter describes the development and psychometric properties (reliability, validity, and fairness) of the Conners Adult ADHD Rating Scale 2nd Edition Short (CAARS™ 2–Short). The CAARS 2–Short aims to assess core and associated symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) with more brevity than the full-length version of the test. Short forms can improve efficiency, decrease administration time, and reduce the cognitive load that can occur with long form tests (Maloney et al., 2011; Pfeiffer et al., 2011). This chapter details the development of the CAARS 2–Short (including item selection and score creation) and the psychometric properties of the shortened measure. Note that the CAARS 2–Short also includes the Negative Impression Index (see chapter 6, Development, for details about the creation of this index) and the ADHD Index (see chapter 12, CAARS 2–ADHD Index). As described in chapter 1, Introduction, the CAARS 2–Short includes brief versions of the Content Scales, two indices of Response Style, the ADHD Index, and the open-ended Additional Questions.

Although correlations between the CAARS 2–Short and the full-length CAARS 2 are high, psychometric properties of full-length forms are not transferrable to abbreviated versions of a test (Smith et al., 2000; Ziegler et al., 2014). Therefore, the reliability, validity, and fairness of the CAARS 2–Short Content Scales were assessed using the same methodology that was applied to the full-length CAARS 2.