This study tests whether the impact of alcohol advertising exposure on intentions to drink and actual consumption is mediated by cognitive responses to advertising messages and positive expectancies about alcohol use. The model was tested using survey data of two important age cohorts, 15 to 20 years (n=608) and 21 to 29 years (n=612). The findings show that alcohol advertising was influential in shaping young people's attitudes and perceptions about alcohol advertising messages. The attitudes and perceptions predicted both positive expectancies and intentions to drink of those under the legal drinking age, but did not affect the young adults' expectancies and consumption. Positive expectancies were powerful predictors of intentions to drink and consumption for both groups. The effects of alcohol advertising on intentions to drink of those aged 15 to 20 years were mediated by cognitive responses to advertising messages and positive expectancies. The mediation effect was not evident among those between 21 and 29 years.