The subjective experience of positive and negative effects of e-cigarette use has been shown to relate to e-cigarette use outcomes in adults, but no validated measure of e-cigarette subjective response exists for adolescents and young adults (AYAs). In the current study, the psychometric properties of the Modified E-cigarette Evaluation Questionnaire (MECEQ) were evaluated for use with AYAs. 997 AYAs who endorsed using nicotine e-cigarettes at least 4 days per week completed an anonymous, online survey in 2022 (51.1% male; 17.39 [1.88] years old; 33.9% Hispanic; 68% White). Analyses included factor analysis to determine the latent structure of the MECEQ, internal consistency, measurement invariance, between-group differences, and test-criterion relationships with vaping frequency and dependence. The originally-proposed, five-factor structure and a novel four-factor structure were supported, and each subscale was internally consistent. Both models reached scalar invariance for all participant subgroups tested (e.g., sex, daily vaping status), and several between-groups differences were observed. For instance, compared to less frequent vaping, daily vaping was associated with increased Craving Reduction (5-factor), reduced Stimulant Effects (4-factor), and reduced Aversion (5-factor; 4-factor). Adjusted relationships between both MECEQ versions and vaping frequency and dependence provided evidence of concurrent validity. Similar to adults, a five-factor and four-factor version of the MECEQ were supported and evidenced internal consistency, scalar measurement invariance, and concurrent relationships with vaping frequency and dependence. Moving forward, researchers are encouraged to include the MECEQ in future studies to better understand the importance of subjective response in AYA vaping behavior. The Modified E-cigarette Evaluation Questionnaire (MCEQ), an e-cigarette-adapted version of the Modified Cigarette Evaluation Questionnaire (MCEQ), recently was validated to assess subjective e-cigarette effects among adults. Here, we demonstrate that the MECEQ can be used among adolescents and young adults (AYAs). The MECEQ can be scored using the original, five-factor MCEQ structure or using a novel, four-factor structure. Both versions were internally consistent, reached scalar measurement invariance, and evidenced concurrent relationships with vaping frequency and dependence. In sum, this study provides the field with the first psychometrically-sound measure of subjective effects of e-cigarette use for use with AYAs.