Purpose: This study is a formative evaluation of an adolescent online e-cigarette prevention program (Clearing the Vapor) giving attention to identifying higher risk adolescent populations, confirming the theory of change, and assessing short-term outcomes. Design/methodology/approach: The evaluation was conducted using online pre-test and post-test survey data collected from adolescent program participants age 10-18 from 2019 to 2021. Analyses included risk ratios on perceived risk, self-efficacy, and behavioral intentions across demographic variables. Pre-test and post-test comparisons were conducted with analysis involving the t-test and the McNemar test. Findings: Prevalence of e-cigarette use was higher among males, older adolescents, and in racial/ethnic groups other than Whites and Asians. Adolescents with lower confidence to say "no" were more likely to use e-cigarettes. Greater perception of harm by using e-cigarettes increased the likelihood of adolescents feeling competent to explain to peers the harmful effects of e-cigarettes. Mean change in commitment levels to not use e-cigarettes increased for males and females, all ages, and racial/ethnic groups other than non-Hispanic Blacks and American Indians. Improvement in non-Hispanic Whites was significantly greater than for non-Hispanic Blacks, American Indians, and Hispanics. Originality/value: Improvement in programming should give careful attention to the incorporation of more prevention activities and to materials tailored specifically to racial/ethnic participants. As a theory of change, findings support the utility of the Clearing the Vape prevention programming to address perceptions of harm that e-cigarettes are safe, confidence in explaining the harmful effects of use, and the development of skills to resist use.