While many standardized assessment measures exist to track child mental health treatment outcomes, the degree to which such tools have been adequately tested for reliability and validity across race, ethnicity, and class is uneven. This paper examines the corpus of published tests of psychometric properties for the ten standardized measures used in U.S. child outpatient care, with focus on breadth of testing across these domains. Our goal is to assist care providers, researchers, and legislators in understanding how cultural mismatch impacts measurement accuracy and how to select tools appropriate to the characteristics of their client populations. We also highlight avenues of needed research for measures that are in common use. The list of measures was compiled from (1) U.S. state Department of Mental Health websites; (2) a survey of California county behavioral health agency directors; and (3) exploratory literature scans of published research. Ten measures met inclusion criteria; for each one a systematic review of psychometrics literature was conducted. Diversity of participant research samples was examined as well as differences in reliability and validity by gender, race or ethnicity, and socio-economic class. All measures showed adequate reliability and validity, however half lacked diverse testing across all three domains and all lacked testing with Asian American/Pacific Islander and Native American children. ASEBA, PSC, and SDQ had the broadest testing.