Calls for improving transparency across the social science are increasing. One strategy that is gaining momentum in the quest to increase transparency is the practice of preregistering a study and analysis plan prior to conducting a study. In this article, we examine the potential of preregistration as a strategy for increasing transparency in education studies. We review existing registries within the social sciences and provide a rationale for why we need a registry specifically geared towards education studies. Finally, we introduce the Registry of Efficacy and Effectiveness Studies (REES), developed by the Society for Research on Educational Effectiveness (SREE). The goal of REES is to increase transparency for studies seeking to draw causal conclusions within the education research and evaluation community. [This article was published in "Educational Researcher" (EJ1204535).]