Little is known about the correlates and potential causes of very early drinking. The authors proposed this risk theory: (a) pubertal onset is associated with increased levels of positive urgency (the tendency to act rashly when experiencing intensely positive mood), negative urgency (the tendency to act rashly when distressed), and sensation seeking; (b) those traits predict increased endorsement of high-risk alcohol expectancies; (c) the expectancies predict drinker status among fifth graders; and (d) the apparent influence of positive urgency, negative urgency, and sensation seeking on drinker status is mediated by alcohol expectancies. The authors conducted a concurrent test of whether the relationships among these variables were consistent with the theory in a sample of 1,843 fifth grade students. In a well-fitting structural model, their hypotheses were supported. Drinker status among fifth graders is not just a function of context and factors external to children: it is predictable from a combination of pubertal status, personality characteristics, and learned alcohol expectancies.