Assessments that function close to classroom teaching and learning can play a powerful role in fostering academic achievement. Unfortunately, however, relatively little attention has been given to discussion of the design and validation of such assessments. The present article presents a framework for conceptualizing and organizing the multiple components of validity applicable to assessments intended for use in the classroom to support ongoing processes of teaching and learning. The conceptual framework builds on existing validity concepts and focuses attention on three components: "cognitive validity," "instructional validity," and "inferential validity." The goal in presenting the framework is to clarify the concept of validity, including key components of the interpretive argument, while considering the types and forms of evidence needed to construct a validity argument for classroom assessments. The framework's utility is illustrated by presenting an application to the analysis of the validity of assessments embedded within an elementary mathematics curriculum.