Vaping is popular among adolescents. Previous research has explored sources of information and influence on youth vaping, including marketing, ads, family, peers, social media, and the internet. This research endeavors to expand understanding of peer influence. Our hypothesis is that friends' influence on teen vapers' first electronic nicotine delivery systems (ENDS) use varies by demographic variables and awareness of ENDS advertising. In August-October 2017, youth ( 3174) aged 13-18 completed an online survey to quantify ENDS behaviors and attitudes and were invited to participate in follow-up online research in November-December 2017 to probe qualitative context around perceptions and motivations ( 76).

This analysis focused on the ENDS users, defined as having ever tried any ENDS product, from the survey ( 1549) and the follow-up research ( 39). Among survey respondents, friends were the most common source of vapers' first ENDS product (60%). Most survey respondents tried their first ENDS product while "hanging out with friends" (54%). Among follow-up research participants, the theme of socializing was also prominent. ENDS advertising and marketing through social media had a strong association with friend networks; in fact, the odds of friends as source of the first vaping experience were 2 times higher for those who had seen ENDS ads on social media compared with other types of media. The influence of friends is particularly evident among non-Hispanic Whites, Hispanics/Latinos, those living in urban areas, those living in high-income households, those with higher self-esteem, and those who experiment with vaping. These findings support the premise that peer influence is a primary social influencer and reinforcer for vaping. Being included in a popular activity appears to be a strong driving force.