Introduction: Ubiquitous social media use among adolescents has led to concerns about its relationship to risk behaviors, including substance use.

Methods: Data was analyzed from 24,746 participants in the 2018 MetroWest Adolescent Health Survey, a census in 26 Greater Boston high schools. We examined hours of daily social media use, attitudes towards use, and associations with 30-day substance use.

Results: 28.5% of youth report 3+ hours on social media daily (34.2% of females; 22.5% of males). High users were more likely than lower/non-users to report recent substance use, including electronic cigarettes (39.9% vs. 22.6%), alcohol (35.1% vs. 24.0%), marijuana (29.1% vs. 17.0%), prescription pain medicine misuse (3.9% vs. 1.8%), and problem drinking like binging (20.4% vs. 13.3%) and drinking alone (8.0% vs. 4.1%). These linkages remained significant when adjusting for sex, grade, race/ethnicity, and sexual orientation (odds ratios from 1.72-2.34). Associations between social media and substance use were greatest for youth who related social media to social standing and peer relationship quality, including using social media to connect with peers and posting content to get “likes.” The association between social media and substance use was weaker for students who used social media in positive ways, like getting peer support and speaking about important issues.

Conclusions: Adolescents who report higher social media use and feel it results in social pressure are more likely to use substances. Efforts are needed to identify and support these youth in school and non-school settings, including addressing quality of online experiences and related substance use behaviors.