Abstract This MERIT extension to The Impact of Tobacco Control Policies on Health Equity in the United States study (R37CA214787) will provide funding to build upon the research under the parent grant to examine how tobacco policies interact to affect youth smoking disparities, and how tobacco control policies affect youth e-cigarette use and related disparities. The parent grant investigates how tobacco control policies affect smoking initiation and cessation differentially by sex, race/ethnicity, and socioeconomic. The MERIT extension would expand upon the work of the original award by (1) analyzing the potential for different tobacco control policies to interact to affect youth smoking initiation and disparities in initiation, and (2) examining how the implementation of tobacco control policies impact the use of e-cigarettes among youth, and disparities in use by sex, race/ethnicity, and SES. The proposed extension will leverage knowledge and policy databases built during the original grant to carry out the new aims. Knowledge learned from this supplement will help us better understand how policies work together to affect youth smoking disparities, and how policies affect youth e-cigarette use.