The 1999 "Standards for Educational and Psychological Testing" defines validity as the degree to which evidence and theory support the interpretations of test scores entailed by proposed uses of tests. Although quite explicit, there are ways in which this definition lacks precision, consistency, and clarity. The history of validity has taught us that ambiguity risks oversimplification, misunderstanding, inadequate validation, and the inevitable potential for inappropriate interpretation and use of results. This article identifies ways in which the spirit of the "Standards" can be clarified, with the intention of reducing these risks. The article provides an elaboration of the consensus definition, invoking a narrow, technical sense of validity, unique to the professions of educational and psychological measurement and assessment; an assessment-based decision-making procedure is valid if the argument for interpreting assessment outcomes (under stated conditions and in terms of stated conclusions) as measures of the attribute entailed by the decision is sufficiently strong. (Contains 16 footnotes.)