Alsina (2002) stated that education, in general, is the foundation for a meaningful future for students, and mathematics education, in particular, is a primary cornerstone of that education. President George W. Bush emphasized in the State of the Union Address of 2006 that a solid foundation in math is necessary to keep America competitive in the global market. However, results from large studies, such as the National Assessment of Educational Progress (NAEP) and the Trends in International Mathematics and Science Study (TIMSS) indicate that students in the United States are not performing at the same level as international students. As a result, teachers, principals, and even school districts at large must evaluate mathematics curricula and instruction and determine what should be done to improve student achievement in mathematics. Professional development has the potential of influencing teacher behavior and thus changing academic outcomes (Ganser, 2000; Payne & Wolfson, 2000; Wenglinsky, 2002). Marzano (2003) also advocated professional development for teachers and stated that it is a key element of collegiality and professionalism. Therefore, the purpose of this study was to relate a teacher’s participation in the Gateway Institute for Algebra, a professional development activity that was designed and delivered by the Tennessee Department of Education each summer, to student performance on the Math Foundations II end-of-course exam and the Algebra Gateway exam for students in four high schools in a large school district in West Tennessee. Multivariate Analysis of Covariance (MANCOVA) was used to analyze data collected from the High School Mathematics Teacher Survey and student scores on the eighth grade math TCAP, end-of-course, and gateway exam scores. The results were mixed. The mean difference was significant for the treatment group in two pairs and for the control group in the remaining two pairs, with one exception. The mean difference in Algebra I mean scores for pair two of the 10^th grade sample was not statistically significant. Research with a larger sample should be conducted to determine if these findings are generalizable to the population.