The Child and Adolescent Level of Care System/Child and Adolescent Service Intensity Instrument (CALOCUS/CASII) is designed to help determine the intensity of services needed for a child served in a mental health system of care. The instrument contains eight dimensions that are rated following a comprehensive clinical evaluation. The dimensions are risk of harm, functionality, co-morbidity (psychiatric, substance abuse, development disability and medical), environmental stressors, environmental supports, the child's resiliency, and the child and family's willingness to engage in treatment. An algorithm connects the ratings to a level of care recommendation. The instrument specifies six levels of care defined flexibly enough to consider whatever services are available. The results of psychometric testing using raters with a broad range of clinical experience and training from four different systems of care around the country are presented. The testing demonstrates excellent reliability when rating vignettes. Using children and adolescents in live system of care clinical settings, the CALOCUS/CASII demonstrates reasonable validity when compared with the Child Global Assessment Scale, and the Child and Adolescent Functional Assessment Scale.