The present research is a third-party study of the effects of the School Renaissance (SR) comprehensive school reform (CSR) model on student achievement in 11 elementary and middle schools in Texas. The primary measures used in the study were the Texas Learning Index (TLI) reading and mathematics scores obtained through administration of the Texas Assessment of Academic Skills (TAAS). The context for the study was the McKinney Independent School District (MISD). Implementation of Reading Renaissance in MISD elementary schools began in the spring, 2000 and was mandated in all district schools in the fall, 2000. The mathematics program was subsequently mandated in all schools in January 2002. Given the cooperation of MISD, the Texas Education Agency (TEA), and superintendents from 10 other Texas school districts, a matched treatment-control pretest-posttest design was employed to address the following primary research questions: (1) How do SR schools compare to matched Comparison schools (C) in student achievement on the Texas Assessment of Academic Skills? (2) Do SR effects relative to C schools vary for (a) reading and mathematics and (b) elementary and middle schools? (3) Do SR effects vary for different types of students? and (4) Do SR effects relative to C schools vary as a function of the degree of SR model implementation? Major conclusions from the study include: (1) In the elementary grades, SR schools showed a clear trend of improved performance; (2) In the middle school grades, SR schools had noticeably improved performance relative to C schools when viewing separate cohorts in both reading and mathematics, although performance was significantly better only in mathematics in the 2002 8th grade longitudinal cohort; (3) Descriptive data showed trends for higher SR than C gains in both reading and mathematics for both 2001 and 2002 cohorts in the free or reduced-price lunch subgroup and in the limited-English-proficiency subgroup but the reverse was true for the 2002 cohort in the low-achieving subgroup; and (4) Implementation intensity was positively related to SR program effects on both reading and mathematics scores. As a whole, these results are suggestive of its benefits for student achievement, and if consistently replicated in future studies would strongly imply proven effectiveness as CSR model. Results also imply that program impacts are significantly more positive when implementation intensity is high. In view of the overall positive results obtained in this study, it is recommended that future research examine school environment variables such as school climate and teacher buy-in to better explain varied program effectiveness across schools and identify the optimum conditions for schools to realize benefits from SR adoption. Summary of Student Sample Sizes is appended. (Contains 47 figures and 17 tables.)