The CGAS is a scale that assesses the global functioning and severity of mental illness in children and adolescents ages 4-16. It evaluates psychological, social, and occupational functioning based on interviews with parents, educators, and the child, as well as observations. Scores range from 1-100, with lower scores indicating greater impairment. While the CGAS has strengths such as being free, easy to use, and measuring functioning in multiple domains, it also has weaknesses including moderate inter-rater reliability in clinical settings and subjectivity from parents and clinicians.