Jorge, Kelly OlivaCota, Luís OtavioFerreira, Efigênia Ferreira eVale, Miriam Pimenta doKawachi, IchiroZarzar, Patrícia Maria2019-08-292015Jorge, Kelly Oliva, Luís Otavio Cota, Efigênia Ferreira e Ferreira, Miriam Pimenta do Vale, Ichiro Kawachi, and Patrícia Maria Zarzar. 2015. “Tobacco Use and Friendship Networks: A Cross-Sectional Study among Brazilian Adolescents.” Ciência & Saúde Coletiva 20 (5): 1415–24. https://doi.org/10.1590/1413-81232015205.13542014.1413-81231678-4561http://nrs.harvard.edu/urn-3:HUL.InstRepos:41275570Aim: To determine the prevalence of tobacco use and its association with types of friendship networks, socioeconomic status and gender among Brazilian adolescents. Methods: A cross-sectional study was carried out with a representative sample of 905 students aged 15 to 19 years. Information on social networks and tobacco use was collected by the self-administered questionnaire 'Alcohol, Smoking and Substance Involvement Screening Test" and the question "What is your most important group of close friends?'. Socioeconomic status was assessed using an area-based social vulnerability index and type of school. Multinomial logistic regression analysis was employed to test associations between tobacco use and the independent variables. Results: The overall prevalence of tobacco use was 18.9%. Female adolescents had 3.80-fold greater odds of reporting weekly to daily tobacco use compared to male adolescents. Participants who reported that their most important groups of close friends were from church had a lower risk of reporting weekly to daily tobacco use in comparison to those who reported that their best friends were from school. Conclusions: The prevalence of tobacco use was high and was associated with school-based (as compared to church-based) friendship networks, female gender and higher area-level socioeconomic status.en-USJournal Article2019-08-2910.1590/1413-81232015205.13542014