The frequent criticisms of the “gateway hypothesis” have led scholars to note the importance of considering the role of intra-individual change for drug use progression. While studies employing drug use trajectories have added considerably to our understanding of drug use comorbidity, the extent to which trajectories inform drug use progression remains largely unknown despite the fact that there are several theoretical reasons to suspect that intra-individual change is important to the gateway phenomenon. The current study employs latent class growth models using a sample from the Boys Town study of adolescent drug and drinking behavior. The results demonstrate that knowing how gateway drug use changes over time provides important information above and beyond knowing frequency of gateway use for predicting harder drug use trajectories. Implications of the empirical findings and directions for future research are discussed.