The impetus for developing the original Conners Adult ADHD Rating Scales (CAARS) was the authors’ need for a better tool to assess the rising numbers of adults presenting to the ADHD Clinic at Duke University Medical Center in the mid-1990s. The scale development process built upon Keith Conners’ seminal work creating gold-standard rating scales for ADHD in childhood. Upon its 1999 release, the CAARS was among the first clinically developed adult ADHD scales with sound psychometric properties based on a sizable normative sample. Since that time, the CAARS has become a popular and widely respected measure used around the world and translated into multiple languages¹ to assess adults for ADHD, monitor progress, and evaluate the efficacy of pharmacologic treatments in clinical trials.

The two decades that have elapsed since the release of the original CAARS have witnessed considerable growth in both our scientific understanding of adult ADHD and the sophistication of rating scale measures to assess mental health disorders. Updating the CAARS to reflect advances in both areas required a complete revision and re-standardization, including (but not limited to) generating and testing hundreds of new and revised items, collecting extensive normative data from the general population, collecting comparison data from relevant clinical samples, evaluating items and language for inclusiveness and equity, integrating statistical analyses and clinical considerations to select the final items, reviewing the resulting scale, determining the measure’s underlying factor structure and psychometrics (including fairness testing to ensure lack of bias against selected demographic groups), and developing scoring and report-generating software (see chapter 6, Development, for a detailed description of the development of the CAARS 2).

Building upon the strong foundation provided by the original CAARS, the comprehensively revised CAARS 2 provides an invaluable tool for assessing core and associated features of ADHD across the full span of adulthood. The remainder of this manual details the administration, scoring, interpretation, development, standardization, and psychometric properties of the CAARS 2.