This edited volume introduces the latest advances in quantitative methods and illustrates ways to apply these methods to important questions in substance use research. The goal is to provide a forum for dialogue between methodologists developing innovative multivariate statistical methods and substance use researchers who have produced rich data sets. This innovative volume: -introduces the use of latent curve methods for describing individual trajectories of adolescent substance use over time; -explores methods for analyzing longitudinal data for individuals nested within groups, such as families, classrooms, and treatment groups; -demonstrates how different patterns of missing data influence the interpretation of results; -reports on some recent advances in longitudinal growth modeling; -illustrates methods to assess mediation when there are multiple mediating pathways underlying an intervention effect; -describes methods to identify moderating relations in structural equation models; -demonstrates the use of structural equation models to evaluate a preventive intervention; -applies epidemic modeling techniques to understand the spread of substance use in society; -illustrates the use of latent transition analysis to model substance use as a series of stages; and -applies logistic regression to prospectively predict smoking cessation.