Three studies are described that assess elements of a new model of adolescent health-risk behavior, the prototype/willingness (P/W) model (F. X. Gibbons & M. Gerrard, 1995, 1997). The 1st analysis examined whether a central element of the prototype model, behavioral willingness, adds significantly to behavioral expectation in predicting adolescents' smoking behavior. The 2nd set of analyses used structural-equation-modeling procedures to provide the 1st test of the complete model in predicting college students' pregnancy-risk behavior. Finally, the 3rd study used confirmatory factor analysis to assess the independence of elements of the model from similar elements in other health behavior models. Results of the 3 studies provided support for the prototype model and, in particular, for 2 of its primary contentions: (a) that much adolescent health-risk behavior is not planned and (b) that willingness and intention are related but independent constructs, each of which can be an antecedent to risk behavior.