Achieve 3000 is an online differentiated reading program for students with disabilities and English Language Learners in grades 6-8. The software delivers differentiated assignments at 12 different reading levels. The software features internal assessments that continuously gauge students' reading levels, provides feedback to teachers, and automatically adapts content as Lexile levels change. Students practice 20 minutes per day, five days a week. The purpose of this paper is examine the extent of the impact of the Achieve 3000 program on the Miami-Dade County Public Schools (M-DCPS) students with disabilities in traditional (non-charter) Miami-Dade County Public Schools who used it during the 2013-14 school year. This analysis of the dose response and impact of Achieve 3000 examined the reading achievement of students with disabilities who worked with the application during the 2013-14 school year. The analysis compared participating students' posttest scores, at each of three levels of activity completion, to the posttest scores of a reference group, controlling for usage, initial ability, and demographic differences; and also compared their performance with that of similar students in similar schools who did not use the software. The findings indicate that the application did not improve the achievement of the students who used it.