There is a need for more knowledge of valid and standardized measures of mental health problems among children and adolescents with intellectual disability (ID). In this study, we systematically reviewed and evaluated the psychometric properties of instruments used to assess general mental health problems in this population. Following PRISMA guidelines, we reviewed empirical research published from 1980 through February 2020 with an updated search in March 2021 in Medline, Embase, PsycINFO, Health and Psychological Instruments, CINAHL, ERIC, and Web of Science databases. Forty-nine empirical articles were included in this review. Overall, the review indicated consistently better documentation of the reliability and validity of instruments designed for the ID population compared to instruments developed for the general child population.