The conventional focus of validity in educational measurement has been on intended interpretations and uses of test scores. Empirical studies of test use by teachers, administrators and policy-makers show that actual interpretations and uses of test scores in context are invariably shaped by local users' questions, which frequently require attention to multiple sources of evidence about students' learning and the factors that shape it, and depend on local capacity to use such information well. This requires a more complex theory of validity that can shift focus as needed from the intended interpretations and uses of test scores that guide test developers to local capacity to support the actual interpretations, decisions and actions that routinely serve local users' purposes. I draw on the growing empirical literature on data use to illustrate the need for an expanded theory of validity, point to theoretical resources that might guide such an expansion, and suggest a research agenda towards these ends.