Longitudinal data analysis in education is the study growth over time. A longitudinal study is one in which repeated observations of the same variables are recorded for the same individuals over a period of time. This type of research is known by many names (e.g., time series analysis or repeated measures design), each of which can imply subtle differences in the data or analysis, but generally follows the same definition. The purpose of this paper is to provide an overview of longitudinal data analysis in education for practitioners, administrators, and other consumers of educational research, focusing on: the purposes of longitudinal data analysis in education, some of its benefits and limitations, and the various analyses used to model student growth trajectories.