Flavored e-cigarettes have received high attention across social and news media. How does exposure to e-cigarette flavors across multiple sources in the media environment influence youth e-cigarette perceptions? To address this question, we identified e-cigarette flavor mentions on 24.3 million Twitter posts and 11,691 longform texts (newspapers, broadcast news, and websites) disseminated over 3 years (2014-2017). During the same period, we measured e-cigarette beliefs through a nationally representative randomly sampled rolling survey of 13-26-year-olds (N = 4,470, 1013 days). We estimated the association between flavor-specific content on Twitter and longform sources in the 28 days prior to each survey date and perceptions that e-cigarettes taste good. The interaction of coverage on Twitter and longform sources was significantly associated with more favorable perceptions of e-cigarette taste (OR = 1.21; 95% CI, 1.04-1.41); the main effects of each source type were not significant. This study presents a novel approach to evaluating the effects of cross-source coverage in today's complex media landscape and may strengthen claims for media influence on e-cigarette use.