The thought of Samuel Messick has influenced language testing in 2 main ways: in proposing a new understanding of how inferences made based on tests must be challenged, and in drawing attention to the consequences of test use. The former has had a powerful impact on language-testing research, most notably in Bachman's work on validity and the design of language tests. Messick's writing on test consequences has informed debate on ethics, impact, accountability, and washback in language testing in the work of several researchers. But the character of Messick's work challenges us in many additional ways. Messick located validity theory in the area of values. This article explores the implications of this position, highlighting the social construction of language test constructs. Language test constructs are increasingly the target of policy, a development that threatens to render traditionally conceived validation work of only marginal relevance. The less obvious, covert social construction of language test constructs is explored in the light of Butler's theory of performativity. The article concludes with a consideration of recent adaptations of Messick's work in the influential validation models of Mislevy and Kane, and considers their failure to address questions of values and the social context of assessment properly. Tackling these questions is the ongoing challenge of Messick's legacy. (Contains 4 footnotes and 2 tables.)