This article contributes to the debate over values in science. A critical co-constructivist framework is proposed for conceptualizing the role that debate over values plays in all science. Using the psychological literature on moral development, it is shown that although debate over values is an integral part of all scientific discourse, it plays a more explicit role in fields within the human sciences (e.g., anthropology, psychology, sociology, etc.) that touch on moral phenomena. Debate over values thus raises a central issue for modern science, namely the need to develop consensually agreed-on methods for resolving such debate. (PsycINFO Database Record (c) 2012 APA, all rights reserved