The purpose of this study was to compare the achievement of students in 14 Pascagoula schools and 9 Biloxi schools implementing School Renaissance (SR) to that of students in matched control schools. The achievement measures to be examined were from the 2004 administration of the Mississippi Curriculum Test (MCT) for Reading, Language Arts, and Mathematics in grades 2-8 and the Mississippi Writing Assessment (WA) in grades 4 and 7. Results showed that, although program effects were not as strong and consistent as in the prior school year, they remained generally positive: 16 out of 20 computed effect size estimates were positive. In both Reading and Language Arts, significant positive program effects were observed in 5th grade and 8th grade. In Mathematics, a strong, significant program effect was observed in 3rd and 6th grades. As in 2002-03, strong, significant program effects were obtained in both tested grade levels, particularly in 4th grade, on the Writing Assessment. Supplementary analyses examined outcomes separately by school district, and examined the relationship of student-level implementation measures to achievement effects. Results showed stronger and more consistent program effects in Reading, Language Arts, Math, and Writing for Biloxi than for Pascagoula. Further, implementation measures (particularly reading level and comprehension scores) accounted for substantial variance in achievement, especially in lower grades. These results overall indicate generally positive and sustainable impacts of SR on student performance in program-independent, high-stakes testing. However, these impacts were predominantly evident in Biloxi and only minimally so in Pascagoula, thus suggesting that sustained implementation (four years vs. two years, respectively) was critical to success. Assessment Scoring Rubrics are appended. (Contains 10 figures and 7 tables.)