Abstract: Online reading instruction tools have proliferated in recent years. Many of the available applications have little or no empirical evidence of effectiveness. During the 2014-2015 school year, we conducted an efficacy study of the online Integrated Reading Activities provided as part of a supplemental instruction system. The Reading Activities were designed to improve reading skills across the curriculum. A diverse sample of teachers, from a variety of school settings, were asked to provide quantitative effectiveness ratings. Teachers rated the effectiveness of the application and its components and offered feedback on the Reading Activities.