During the 2017-2018 school year, SEG Measurement conducted a study of the effectiveness of Imagine Language & Literacy, an online system that provides individualized adaptive instruction and breaks down skills into component parts to help students become proficient readers. The study was conducted in three districts in Texas. Research indicates that computer assisted instruction can positively impact students' performance in language and literacy development (Cassady & Smith, 2004; 2005; Cheung & Slavin, 2011; Macaruso & Rodman, 2011). Imagine Language & Literacy is instructional software designed to build language and literacy skills among students in kindergarten through sixth grade. To improve language and literacy achievement, Imagine Learning features instruction in phonemic awareness, phonics, vocabulary, fluency, comprehension, grammar, and language development (both academic and conversational). Research indicates that Imagine Language & Literacy has a positive effect for literacy development among English language learners in grades K-5, for all students in grades K and 1, and for struggling readers in grades 2 and 3 (Cassidy, Smith, and Thomas, 2017; Elliot, S. 2014; Hobbs, 2016; Hobbs 2017). To date, effectiveness studies have not focused on the performance of students in fourth and fifth grade. The purpose for this research was to describe program impact for fourth and fifth grade students in Texas who used Imagine Language & Literacy as supplemental reading instruction. The study employed a quasi-experimental design with matched groups to compare the growth in reading skills between those students who used Imagine Language & Literacy as a supplemental part of their reading instruction (treatment group) and comparable students who did not use Imagine Language & Literacy as part of their reading instruction (control group). The growth in reading skills was assessed using the State of Texas Assessments of Academic Readiness (STAAR) Reading. Students' spring 2017 STAAR Reading scores served as the pretest and spring 2018 STAAR Reading scores served as the posttest. Treatment and control group participants were statistically matched using propensity score matching. 1,282 fourth grade students and 1,064 fifth grade Texas students participated in the study. The reading skills growth in the treatment group and the control group was compared statistically using analysis of covariance (ANCOVA). Specifically, we examined the difference in the Spring STAAR Reading 2018 scores (dependent variable) between the treatment and control groups (independent variable) while controlling for the initial ability of the students from Spring 2017 STAAR Reading (covariate). Students who used Imagine Language & Literacy showed significantly more growth in reading skills than comparable students who did not use Imagine Learning. Fourth grade students using Imagine Language & Literacy showed about 33 points more growth on the assessment, or 0.24 standard deviations (ES=0.24), than did fourth graders not using Imagine Learning. Fifth graders showed about 19 points more growth on the assessment, or 0.14 standard deviations (ES=0.14), than did nonusers. [This report was prepared by SEG Measurement.]