This is a summative report based on Year Three data from the MSP Grant Project entitled, “Content Development for Investigations” (CoDE:I). The purpose of the MSP grant program was to develop standards-based elementary mathematics teachers by giving teachers the tools to teach with a new standards-based mathematics curriculum, Investigations in Number, Data, and Space (Investigations). The participants were teachers in two school systems located near a large metropolitan city in the southeastern United States. System One is a large, urban school system and System Two is a smaller suburban school system in a neighboring city. The two school systems conducted professional development separately and on different days throughout the grant program, but the overall content and focus of the professional development remained consistent. The professional development facilitators worked with both groups of teachers. Since the MSP project is not a longitudinal design, teachers participants exit from the program at the end of the academic year. As a result, it is not necessary to combine the data from three years unless we want to examine the cohort effect. The focus of this report is to examine the impacts of the professional development on teacher beliefs, practices, mathematics content knowledge, and student learning outcomes.