There is a widespread view that one does either theory or empirical work, and that theory and empiricism represent distant concerns, opposing worldviews, and perhaps distinct mentalities or personalities. This prevalent view has deep roots and is also the result of pragmatic and understandable tendencies toward division of intellectual labor. Against this view, this essay suggests that the relations between theory and empirical study ought to be understood as more intimate and that making legal theory an explicit focus can improve empirical scholarship. We pursue this claim by articulating a basis for legal theory and by showing how that basis illuminates both the application and design of empirical research on law. Legal theory, we argue, follows jurisprudence in interrogating the law as a set of coercive normative institutions. The upshot of this approach is a recognition that an interdisciplinary analysis of law must rely on both a theory (explicit or implicit) of the way law's power and its normativity align and an account of the way in which this discursive cohabitation manifests itself institutionally. We thus argue that legal theory is necessary in order to draw fruitfully on empirical research and further claim that legal theory provides guidance both for setting up an empirical research agenda on law and for designing research into specific topics.