This manual is intended to improve both the design of longitudinal studies and analysis of the resulting data. Issues related to educational and developmental research have been emphasized in these eight chapters. Topics of particular interest to longitudinal researchers include stochastic models of developmental change, mathematical representation of growth curves, structural equation models, analysis of univariate and multivariate variance, and analysis of categorical data. The differentiation between intraindividual variation, interindividual differences, and interindividual differences in intraindividual change is also discussed. (Author/GDC)