Performance assessments, long a staple of industrial and military applications, are becoming increasingly popular as purported instruments of standards-based education reform because they promise positive consequences for teaching and learning. In this new policy arena, performance assessments, like all applied assessments, must be justified in terms of validity, reliability, comparability, and fairness -- not just because these are important psychometric principles, but because they are social values that have meaning and force outside of measurement whenever evaluative judgments and decisions are made. This paper delineates six aspects of construct validity that, in effect, provide standards of validity for all educational and psychological measurement, including performance assessments.