McCabe SE, et al. - Given the highest prevalence of prescription drug misuse during young adulthood (ages 18–25 years), researchers sought to ascertain prescription drug misuse trajectories for three drug classes (opioids, stimulants, and sedatives or tranquilisers) from adolescence into adulthood. In addition, they investigated the extent to which different trajectories are connected with symptoms of substance use disorder and explored the factors linked with high-risk prescription drug misuse trajectories. In this longitudinal multi-cohort study, they followed nationally representative probability samples of 51,223 adolescents in the USA across eight waves from age 18 years (cohorts 1976–96) to age 35 years and recognized heterogeneity in prescription drug misuse trajectories. Five prescription drug misuse trajectories were recognized which differed in the age at which past-year prescription drug misuse high frequency peaked: rare or no misuse at any age, peak at age 18 years, peak at ages 19–20 years, peak at age 23–24 years, and peak at ages 27–28 years. Each prescription drug class was observed to have similar prescription drug misuse trajectories. The strong risk factor for the development of substance use disorders during adulthood was any high-frequency prescription drug misuse, particularly later-peak prescription drug misuse trajectories. In light of these findings, practitioners may recognize people at highest risk for substance use disorders and target intervention strategies.