This study examined teacher perceptions of the impact of intervention factors implemented during a grant-funded mathematics education initiative. Participant teachers identified both the interventions that most influenced their initial change to the use of standards-based mathematics practices, as well as the interventions that helped to sustain their use of standards-based mathematics. A researcher-developed survey instrument collected data from 199 elementary classroom teachers who have been involved with a major grant-funded mathematics change initiative, awarded to Rapid City Area Schools in Rapid City, South Dakota. Five-point Likert-type scales measured teacher perceptions of the impact of the following intervention factors: district-level classes, building-level classes, classroom coaching, day to day use of research-based instructional materials, district-level administrative support, building-level administrative support and student success as measured informally by teachers during the day-to-day practice of teaching, student success as measured by formally by the high-stakes state assessment for South Dakota, and student success as measured by a conceptual performance assessment. Overall, the teachers participating in this study reported that the grant had considerable impact on mathematics instruction; interventions were highly valued, and led to a high level of implementation of standards-based mathematics. Basic users, who are in the early stages of implementing standards-based mathematics, find day-to-day use of tested, research-based instructional materials; student learning as measured informally by teachers during the day-to-day practice of teaching; district-level classes; and district-level administrative support to have considerable impact prompting the initial change to standards-based mathematics. Advanced users, who are in the later stages of implementing standards-based mathematics, find day-to-day use of tested, research-based instructional materials; student learning as measured informally by teachers during the day-to-day practice of teaching; district-level classes; classroom coaching; district-level administrative support; and student success as measured by formally by the high-stakes state assessment for South Dakota to have considerable impact on the sustained use of standards-based mathematics. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]