In the present study, 49 fifth-graders enrolled the KIPP D.I.A.M.O.N.D. Academy in the 2002-03 school year were individually matched to control student from five feeder schools on the basis of ethnicity, free-reduced lunch status, and fourth-grade achievement on the Reading and Mathematics subtests of the Tennessee Comprehensive Assessment Program: Achievement Test (TCAP:AT). Although the KIPP and control students had virtually identical means on all fourth-grade tests, the KIPP students outperformed the control students on five out of the six fifth-grade tests. The one exception was the Writing assessment, on which KIPP and control group means were virtually identical. In four of the TCAP:AT tests (NRT-Reading, NRT-Math, CRT-Reading/Language Arts, CRT-Math) the comparisons were statistically significant with effect sizes ranging from +0.31 to +0.63. Across all 6 tests, the median adjusted ES was +0.31, indicating a moderately strong effect. These positive outcomes compare favorably with those from the most successful whole-school reform models (Borman, Hewes, Overman, & Brown, 2002). Findings are discussed with regard to the KIPP components and conditions likely to have increased academic focus and learning in the first implementation year. (Contains 3 tables.)