BACKGROUND: Smoking and alcohol use are risky behaviors that can start early in life. AIM: To determine the lifetime prevalence of tobacco and alcohol use in adolescents aged 10 to 14 years and related factors. SUBJECTS AND METHODS: A survey about smoking and alcohol use was answered by 1,392 teenagers aged 10 to 14 years (46% women) from seven schools in a small city near Santiago. Personal, family, and school factors were evaluated through self-report scales. Smoking and alcohol use, as dichotomous dependent variables, were defined as having consumed any of these substances throughout life. Prevalence was calculated as percentages with 95% confidence intervals. Association analyses were conducted using multivariable logistic regression models. RESULTS: Six and eleven percent of participants reported having smoked and used alcohol in their life, respectively. Smoking was associated with age, having behavioral problems, mothers� smoking, perceiving that parents had drug problems, and not living with both parents. Alcohol use was mainly associated with age, having behavioral problems, perceiving that other students consumed drugs, alcohol use by both parents, and perceiving a lack of family support. CONCLUSIONS: Tobacco and alcohol use is highly prevalent in adolescents aged 10-14 years. There were common risk factors for smoking and alcohol use such as age and having behavioral problems, while other factors were more specific such as mothers� smoking, or parental alcohol use.