The development of the CAARS 2 spanned several years and included the conceptualization, initial planning, and item development phase, the pilot phase, and the standardization phase. The goals for the development of the CAARS 2 included building upon the strong foundations of its predecessor, maintaining its utility for clinicians and researchers while providing updated normative data and item content, and enhancing the format of the rating scales. The CAARS 2 preserves the core strengths of the CAARS to capture features of ADHD in adults and also aligns with the Conners 4 measure of childhood ADHD. The revised measure meets standards for fairness and cultural sensitivity. The CAARS 2 includes updated and more representative normative samples, an ADHD Reference Sample to better facilitate the diagnostic process, a new Response Style Analysis (including validity scales), updated and expanded content, screening items for additional clinical concerns, and items to examine impairment and functional outcomes. Through an extensive, careful development process, the development team was able to achieve their goal of producing a clinically relevant and statistically sound set of rating scales, resulting in an improved tool for assessing ADHD in adults.