In contrast to the cost-benefit, utility-based approach to decision-making implicit in models such as the theory of planned behaviour (TPB), the logic of appropriateness (March, 1994. A Primer on Decision Making: How decisions happen. New York, NY: The Free Press) describes decision-making in terms of heuristic decision rules that involve matching identities to situations. This research is the first to apply the logic of appropriateness in conjunction with the theoretical structure of the TPB and assessed whether a measure of identity appropriateness might independently predict adults' intentions to engage in binge drinking. In Study 1, participants (N = 197) completed questionnaires assessing attitudes, subjective norm, perceived behavioural control, past behaviour, and identity appropriateness in relation to binge drinking. Path analysis revealed an independent predictive effect of identity appropriateness on intentions in addition to an indirect effect via attitudes. In Study 2 (N = 179), a prospective measure of behaviour was included in a similar study: Identity appropriateness again predicted intentions independently of the extended TPB predictors. It was again also found to be a strong predictor of attitudes. We suggest that the notion of identity appropriateness may assist in explaining the capacity of measures of self-identity to predict people's behavioural intentions.