"Odyssey Reading," published by CompassLearning[R], is a web-based K-12 reading/language arts program designed to allow for instructional differentiation and data-driven decision making. The online program includes electronic curricula and materials for individual or small-group work, assessments aligned with state curriculum standards, and a data management system that allows teachers to develop individualized instruction and assessment tools to track individual student and classroom performance. "Odyssey Reading" can be used as a stand-alone curriculum or as a supplement to other reading and language arts curricula. This report focuses on "Odyssey Reading" programs in grades 4 and higher. "Odyssey Reading" for students in grades 4-8 provides instruction in phonics, context, decoding, and comprehension. The What Works Clearinghouse (WWC) identified 27 studies of "Odyssey Reading" for adolescent learners that were published or released between 1989 and 2011. No studies of "Odyssey Reading" that fall within the scope of the Adolescent Literacy review protocol meet WWC evidence standards. The lack of studies meeting WWC evidence standards means that, at this time, the WWC is unable to draw any conclusions based on research about the effectiveness or ineffectiveness of "Odyssey Reading" on adolescent learners. Additional research is needed to determine the effectiveness or ineffectiveness of this intervention. (Contains 6 endnotes.)