The purpose of this study was to examine the relationship of two implementation variables (source of technical support and time of implementation) to first grade reading achievement across three naturally-occurring conditions over a six-year time span. Two of the conditions involved implementation of Direct Instruction (DI) curriculum programs, one with technical support from a purveyor associated with the curriculum's developer and the other with a group not associated with the developer. The third condition involved implementation of another highly rated reading curriculum program: "Open Court." Increases in the vocabulary and comprehension achievement scores of students across all three conditions were statistically significant. Increases in students' scores were significantly greater in the DI implementation conditions relative to the "Open Court" condition. Increases in students' scores were significantly larger in the DI implementation condition with technical support from the purveyor associated with the curriculum developer relative to the group not associated with the curriculum developer. Differences in achievement across the implementation conditions were both statistically significant and educationally meaningful. (Contains 3 figures and 7 footnotes.)