The prevalence of youth vaping has, in a relatively short time, become an “epidemic.” In the wake of such labeling by the Surgeon General, a number of important examinations of vaping have been conducted. These have largely focused on high school and college-age youth as this demographic shows the greatest prevalence of use. Nonetheless, no measure has been made available which might allow for the comprehensive assessment of quantity and frequency of vaping among this age group, thus aiding in standardization across settings. The current study utilized cognitive interviews with high school and college-age youth who use vaping devices to inform the preliminary development of such an assessment. The sample consists of eight students between the ages of 15 and 24 (M = 18.75, SD = 2.73, 62.5% female, 75.0% Hispanic/Latino/a/x, 100.0% White). Interviewing and measure refinement were conducted in a two-phase iterative fashion. Suggestions made during cognitive interviews resulted in the refinement of assessed content type, updated categories and pictures of vaping devices, as well as updated and age-relevant terminology. Further, instructions were streamlined, and assessment items and multiple-choice options were refined to maximize clarity and to minimize participant confusion. The result of this study, the E-Cigarette Assessment for Youth Revised, is a unique tool for standardizing examinations of the quantity and frequency of vaping behaviors among high school students and college-age youth.© 2024 Society for Research on Adolescence.