In this chapter, assessment is considered as it relates to guiding the decisions teachers make about instruction in the classroom. Gickling and Havertape (1982) indicate the four stages of the assessment cycle as screening, identification, instruction, and measurement of progress. Typically, psychoeducational assessment has been focused on the stages of screening (early recognition of problems) and identification (discriminating, based on a normative framework, whether a student requires some kind of special service). Those two types of assessment, which have formed the bulk of the assessment literature in school psychology, do not, however, readily translate in a functional way to teachers who are responsible for a child's instruction (Gickling & Havertape, 1982). We need, therefore, to turn our attention to assessment, that is related to instructional decision making, that is, assessment for instruction and measurement of progress.