Importance: Little is known about the roles of advertising and parental and peer influence in e-cigarette use among US adolescents in recent years, hindering efforts to address the increasing rate of youth vaping.

Question: Are exposure to e-cigarette advertising and parental and peer influence associated with e-cigarette use among US adolescents?

Findings: This cohort study of a total of 11 641 adolescents from the Population Assessment of Tobacco and Health study waves 4, 4.5, and 5, found that adolescents who reported past 30-day e-cigarette advertising exposure and who reported having best friends using e-cigarettes were more likely to feel curious about using e-cigarettes and more likely to initiate e-cigarette use at follow-up.

Meaning: These findings suggest that efforts to address youth vaping need to consider peer influence and incorporate measures reducing e-cigarette advertising exposure.