Online course taking is widespread in K-12 education and even more so as schools have turned to virtual learning during the global health crisis. Educators across the country are actively seeking evidence-based guidance, only to discover that there is limited rigorous research related to online learning. The need to understand how to prepare students to learn in an online environment has become more urgent. Orientations are cited as a best practice; however, there is no causal evidence to support that recommendation. In a randomized controlled trial, we found no significant differences in online course outcomes between high school students who were assigned an orientation and those in the business-as-usual group, though the timing of enrollment acts as a moderator. [For the corresponding grantee submission, see ED613269.]