Assessment of low incidence disabilities is a complex process. A score on any test gives an estimate of performance in a particular area, compared to a reference. Standard scores must be interpreted in the wider context of results from a range of diagnostic information sources. Assessments should not be used as a single source of information for diagnostic or intervention decisions. This presentation will review different assessments that can be utilized in a holistic evaluation. Participants will learn how to use clinical validity data as a qualitative source of information. Participants will review the differences between norm-referenced assessments, criterion-referenced assessments, and functional assessments for a variety of low incidence populations, including but not limited to deaf/hard of hearing, visual impairments, intellectual disability, and autism. Participants will learn how to make individualized, student-specific recommendations and interventions for school-based teams.