A quantitative approach was used to investigate the impact of a district-wide, job-embedded mathematics professional development program on elementary teachers' general and personal efficacy. This investigation was based on the principles of mathematics professional development, efficacy theory, and student achievement. It was designed to determine the impact on teachers' personal and general mathematics teaching efficacy as well as the relationship between teachers' personal and general efficacy in teaching mathematics and students' socioeconomic status with students' achievement in mathematics. Teachers' general and personal efficacies were measured using a paired-t analysis on the Math Teaching Efficacy Beliefs Instrument. Student achievement as measured by the state mathematics content test was regressed over the measures of teachers' general efficacy, teachers' personal efficacy, and socioeconomic status. Results indicate teachers' general efficacy and student socioeconomic status predicted student achievement in mathematics, supporting the conclusion that job-embedded, sustained professional development may lead to improved student achievement in mathematics.