An accumulating literature has shown the influence of childhood experiences associated with alcohol use on later drinking practices. Recent studies have suggested that alcohol-related expectancy may serve as an intervening variable to connect these early experiences with the later, proximal decision to drink when opportunities for actual alcohol consumption arise. Those studies, however, have collected expectancy and drinking data concurrently, whereas the present study for the first time reports on the power of expectancies measured in early adolescents (seventh and eighth grades) to predict self-reported drinking onset and drinking behavior measured a full year later. Results show that five of seven expectancy scores readily discriminated between nonproblem drinkers and those subsequently beginning problem drinking and accounted for a large portion of the variance in a continuous quantity/frequency index and a problem drinking index. The strength of these timelagged relations strengthens the case for inferring that expectancies have causal power on drinking behavior and suggests prevention strategies.