This article presents findings from an evaluation of an instructional-technology professional development (PD) program that uses many practices advocated by PD experts. In this multiphase evaluation, evaluators examined the program, determined whether variations in program implementation had an impact on teacher outcomes, and then looked at whether variations in program implementation and teacher outcomes had an impact on student achievement. We found that greater PD fidelity was associated with higher-quality lesson plans and higher student achievement. This evaluation suggests that instructional-technology PD that is closely aligned to a program's core conceptual foundations can lead to positive teacher and student outcomes. (Contains 10 tables and 2 footnotes.)