Standardized testing has been implemented in most school districts as part of an effort to improve student achievement in mathematics, reading, science, and English. There have been heated debates as to the effects of these improvement efforts on student achievement. In studying these issues, it is important to examine longitudinal growth patterns for individuals. In most of the studies, however, there is a lack of empirical data at the individual student level or the studies are cross-sectional in nature. The current study attempts to examine growth patterns of student math achievement between 1997 and 2000 and individual differences in growth patterns. MDS exploratory growth modeling was used in the investigation based on data from 716 students in a single school district. Individual differences in growth rates were found. Disadvantaged (limited English proficiency and special education) students had lower initial achievement levels and did not seem to be catching up to other students because their average growth rates were similar to those of other students. These results are discussed in light of recent school reform efforts and the goal of closing achievement gaps.