The purpose of the present study was to examine the effects of teachers on student achievement using a longitudinal analysis. The analysis was based on the value-added assessment system implemented in Tennessee. In order to conduct this study, data were collected for two sets of students in one school district. The first set of students began Kindergarten in Spring 2000-Spring 2001 and continued to third grade in the Spring 2003-Spring 2004. The second set began Kindergarten in Spring 2001-Spring 2002 and went through second grade in the Spring 2003-Spring 2004 school year. Using mixed model ANOVAs modeled after Sanders' work, data were examined in thirteen separate analyses using nine independent variables. Year-to-year language arts differences, math differences, and reading differences on the ITBS were the dependent variables. In all of the year-to-year models, teachers were found to have a profound impact on student achievement. Prior achievement level was found to be another important factor in student achievement, with higher achieving students making consistently higher year-to-year gains than lower-achieving students.