Existing studies of the impact of home rules on youth\u27s vulnerability to e-cigarette use were based on cross-sectional data, youth or parent reports alone, as well as youth\u27s perceptions and susceptibility. This study capitalizes on the restricted-use data of the Population Assessment of Tobacco and Health (PATH) Study to examine the longitudinal association between home rules for e-cigarette use and youth\u27s vulnerability including initiation of use and regular use two years later. Secondary analysis was conducted on 1203 parent-youth pairs who participated in both Wave 4 (2016-2018) and Wave 5 (2018-2019) assessment of the PATH Study and while the youth were age 12-16 at Wave 4. Linear and logistic regressions were performed to examine the associations between having a strict home rule for e-cigarette use at Wave 4 and the youth\u27s outcomes including perceived social norms, expectancies, susceptibility, initiation of use, and regular use of e-cigarettes at Wave 5, controlling for parent and youth factors. The results show that having a strict home rule for e-cigarette use was associated with youth\u27s heightened level of perceived injunctive norms (β = 0.22, p \u3c 0.01), higher expectancy of harmfulness (β = 0.28, p \u3c 0.01) and lower odds for regular e-cigarette use (OR = 0.36, p \u3c 0.05). In conclusion, the findings of this study support the potential protective effects of implementing a strict home rule for e-cigarette use. Future intervention efforts may promote parents\u27 awareness of the potential protective effects of a strict home e-cigarette rule on youth\u27s normative belief, harm expectancy, and behavior of e-cigarette use
