Taking into account the importance of act prevention on the development of addictions, we assessed the presence of multiple addictions in an adolescent high-school population, also assessing the prevalence of Internet abuse and the impact on disability. Adolescence seems to be a critical period of addiction vulnerability, based on social but also neurobiological factors. The earlier onset of behavioral/substance dependence seems to predict greater addiction severity, morbidity, and multiple addictive disorders. Data were collected from a sample of 275 students in Florence, Italy, high schools through surveys distributed in classes. The sample had an average age of 16.67+/-1.85 years (52.4% males, 47.6% females). To assess multiple addiction we used the 16 subscales of the Shorter PROMIS Questionnaire, to assess Internet addiction prevalence we used the Internet Addiction Scale, and to quantify disability symptoms, we used the Sheehan Disability Scale. Caffeine abuse, sex, relationship submissive, gambling, food starving, and food bingeing have raised highest scores. 5.4% of the students were found to be Internet addicted similar to other countries. Disability seemed strongly correlated to the subscale of alcohol, gambling, sex, tobacco, food starving and food bingeing, shopping, exercise, and Internet addiction. Gambling, sex, caffeine abuse, compulsive help dominant, work, Internet addiction, relationship dominant, and relationship submissive in this sample were strongly related to substance dependence. Level of concerns unexpected compared to the level reported in other countries for the behavioral compulsions, have been highlighted. Behavioral addictions are multiple, a source of disability, and they are related to substance abuse. It has yet to be clarified if they are a temporary phenomenon occurring in adolescents or if they are a stable trait, accounting as marker for the development of substance abuse.