Literacy skills are critical to students' academic achievement and setting them on a path to successful high school graduation and readiness for college and careers. "Web-Based Intelligent Tutoring for the Structure Strategy" ("ITSS") is a supplemental web-based program for students in grades K-8. It is designed to develop literacy skills needed to understand factual texts encountered in classrooms and everyday life. The program teaches students how to follow the logical structure of factual text and to use text structure to improve understanding and recall. This What Works Clearinghouse (WWC) report, part of the WWC's Adolescent Literacy topic area, explores the effects of "ITSS" on comprehension. The WWC identified two studies of "ITSS" that meet WWC standards. The evidence presented in this report is from studies of the impacts of "ITSS" on students in grades 4, 5, and 7 and a variety of school settings, including suburban and rural districts. [For the Intervention Brief, see ED604233. For the Intervention Snapshot, see ED604234.]