The Transtheoretical Model of Change has been proven very effective in explaining both the acquisition and cessation of many health related behaviors. In this study, this model was applied to the domain of immoderate alcohol use among adolescents (usually drinking three or more drinks per occasion). Measures for two constructs of the model were developed: Stage of Change and Decisional Balance. A total of 853 tenth and eleventh graders who attend vocational training programs were administered a 37-item decisional balance questionnaire and a 5-item staging measure. A short (16-item) psychometrically sound Decisional Balance Inventory was developed based on an exploratory factor analysis that identified two factors, the Pros and Cons of Alcohol Use. The factor structure was confirmed using structural modeling techniques on a hold-out sample. Based on a combination of model fit and parsimony considerations, an uncorrelated model was selected (IFI2 = .909). Students were classified into one of nine stages of acquisition or cessation. External validity was established by the significant and meaningful differences between the stages of change on the pros and cons of alcohol use. Implications of this research are discussed.