This cross-sectional study consisted of a national sample of 12,000 Norwegian adolescents aged 12-20 years. Data on violent behavior, alcohol intoxication, and various confounders were obtained by self-administered questionnaires; 2.8 percent of the adolescents had been in a fight with a weapon, and 32.6 percent had assaulted or threatened to assault someone during the past year. Violent behaviors were more often reported by boys in the younger age groups in association with increasing frequency of alcohol intoxication, as well as by users of other drugs, by those engaged in criminal activities, and by those in "wet" environments (friends drinking regularly and parents often being intoxicated). The impact of intoxication frequency on number of times engaged in violent behaviors was of modest magnitude. It was greater in the youngest age group compared to those in the middle and late teens, and greater for boys than for girls. However, when the study controlled for criminal activities, the adjusted effect of intoxication on violent behavior was significantly reduced; the effect was then of the same magnitude for both genders, and there was no longer any significant effect for the youngest age group. Also, controlling for parents' and friends' drinking and parental monitoring did not alter these findings. The study concludes that a small direct effect of alcohol intoxication on violent behavior apparently remains after controlling for various relevant confounders in middle and late teens; however, possible indirect effects of alcohol intoxication, mediated by a deviant lifestyle and "wetness" of environment, should also be taken into account. 6 tables and 75 references