The SuccessMaker[R] program is a set of computer-based courses used to supplement regular classroom reading instruction in grades K-8. Using adaptive lessons tailored to a student's reading level, SuccessMaker[R] aims to improve understanding in areas such as phonological awareness, phonics, fluency, vocabulary, comprehension, and concepts of print. The computer analyzes students' skills development and assigns specific segments of the program, introducing new skills as they become appropriate. As the student progresses through the program, performance is measured by the probability of the student answering the next exercise correctly, which determines the next steps of the lesson. What Works Clearinghouse (WWC) reviewed 26 studies on SuccessMaker[R]. Thirty-three do no meet WWC evidence standards or eligibility screens. The remaining three studies meet WWC evidence standards with reservations. The three studies included 450 students, ranging in age from nine to 16 years, who attended elementary, middle, and middle-high schools in Alabama, Illinois, and Virginia. Based on the three studies, the WWC found no discernible effects in alphabetics and reading fluency, and potentially positive effects in comprehension and general literacy achievement. The three studies that met WWC evidence standards with reservations are: (1) Beattie, K. K. (2000). The effects of intensive computer-based language intervention on language functioning and reading achievement in language-impaired adolescents (Doctoral dissertation, George Mason University, 2000). "Dissertation Abstracts International," 61(08A), 194-3116; (2) Campbell, J. P. (2000). A comparison of computerized and traditional instruction in the area of elementary reading (Doctoral dissertation, University of Alabama, 2000). "Dissertation Abstracts International," 61(03A), 77-952; and (3) Gallagher, E. M. (1996). Utilization of an ILS to increase reading comprehension (integrated learning systems, CAI) (Doctoral dissertation, Northern Illinois University, 996). "Dissertation Abstracts International," 58(05A), 79-1591. Six appendixes are included: (1) Study characteristics; (2) Outcome measures by domain; (3) Summary of study findings included in the rating (by domain); (4) Summary of subgroup findings for the comprehension domain; (5) Ratings by domain; and (6) Extent of evidence by domain. (Contains 12 footnotes.)