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Methods| Participants were current smokers recruited from the Knowledge Networks (now GfK) 6 probability-based webenabled panel who completed baseline (November 2011) and follow-up (November 2012) surveys. Of the 1549 participants from the 2011 survey who remained on the panel in 2012, 1189 were smokers and 81.3% completed the follow-up survey. Respondents who provided nonsensical data were excluded, yielding 949 participants. The institutional review board of the University of California, San Francisco, approved the study; all participants provided written electronic informed consent. Baseline e-cigarette use was measured with the yesor-no question,“Other than cigarettes, have you used electronic cigarettes in the past 30 days (even once)?” Cigarettes used per day (continuous variable), time to first cigarette (< 30 vs≥ 30 min) and intention to quit (never, not in next 6 months,