Alcohol use in early adolescence is associated with numerous concurrent and future problems, including diagnosable alcohol use disorders. The trait of negative urgency, the tendency to act rashly when distressed, is an important predictor of alcohol-related dysfunction in youth and adults. The aim of this study was to test a model proposed by Cyders and Smith (2008) specifying a puberty-based developmental increase in negative urgency, which in turn predicts subsequent increases in early adolescent drinking. In a sample of 1,910 youth assessed semi- annually from spring of 5th grade through spring of 8th grade, we found support for this model. Pubertal onset was associated with both a mean increase and subsequent rises in negative urgency over time. Drinking frequency at any wave was predicted by prior wave assessments of drinking frequency, negative urgency, and pubertal onset. The slope of increase in drinking also increased as a function of pubertal onset. This model applied to negative urgency but not to other impulsivity-related traits. These findings highlight the importance of personality change in early adolescence as part of the risk matrix for early onset alcohol consumption.