Smoking is a form of medical addiction, usually adopted during adolescence. The aim was to determine the prevalence of smoking in adolescents, aged 13–18 years old, to investigate their attitudes towards smoking and determine the contribution of social influences to onset and continuation of smoking. An anonymous self-report questionnaire was filled in by 873 high school students of Central Greece. Smoking incidence was 19.2%, with a 13.7% of regular smokers. The presence of a smoker in the family and a smoker friend were correlated with increased smoking rates. School grades were correlated negatively with smoking attitude and positively with allowance. Age was correlated negatively with social influence. Social influence appears stronger on younger ages and is a main determinant of smoking behavior. A more susceptible attitude towards smoking is formed during late adolescence. Certain social predictive factors for attitude towards smoking are proposed.