A prescriptive statement is a recommendation that, if a course of action is taken, then a desirable outcome will likely occur. For example, in reading research recommending that teachers apply an intervention targeted at a specific reading skill to improve children's reading performance is a prescriptive statement. In our view, these statements require thorough scientific understanding of causal relationships that follow from scientifically credible research and are generalizable across varied contexts. In this article, we consider both epistemological issues and research credibility indicators (i.e., internal and external validity issues) that restrict one's ability to make prescriptive statements. After presenting an argument for why prescriptive statements should be made sparingly, we describe a stage model of programmatic educational intervention research that is analogous to medical research's phase model and which emphasizes the importance of including appropriate comparison groups, observing replicated findings across different populations and situational contexts, demonstrating statistical relationships between interventions and outcomes, accounting for and ruling out potential alternative explanations for obtained effects, and ultimately conducting randomized field trials. We conclude with the prescriptive statement that only after achieving these high standards of research credibility should educational researchers offer prescriptive statements.