Objectives University students commonly engage in heavy episodic drinking (HED), which contributes to injury risk, deleterious educational outcomes, and economic costs. Identification of the determinants of this risky behaviour may provide formative evidence on which to base effective interventions to curb HED in this population. Drawing from theories of social cognition and dual-process models, this study tested key hypotheses relating to reasoned and implicit pathways to action for HED in a sample of Australian university students who drink alcohol. Design A two-wave correlational design was adopted. Methods Students (N = 204) completed self-reported constructs from social cognition theories with respect to HED at an initial time point (T1): attitude, subjective norm, perceived behavioural control, intentions, habit, past behaviour, and implicit alcohol identity. Four weeks later (T2), students self-reported their HED behaviour and habit. Results An initial path model indicated attitude and subjective norm predicted intentions, and intentions and implicit alcohol identity predicted HED. Inclusion of past behaviour and habit revealed direct effects of these on HED. Effects of T1 habit on HED were indirect through T2 habit, and there were indirect effects of past behaviour on HED through habit at both time points and the social cognition constructs. Direct effects of intentions and implicit alcohol identity, and indirect effects of attitude and subjective norm, on HED, were attenuated by the inclusion of past behaviour and habit. Conclusion Results indicate that university students' HED tends to be governed by non-conscious, automatic processes than conscious, intentional processes. Statement of contribution What is already known on this subject? Social cognitive factors are associated with risky alcohol consumption behaviours. Dual-process models are being used to explain health behaviours, such as heavy episodic drinking (HED). What does this study add? Past HED behaviour and HED habits have direct and indirect effects on students' HED behaviour. Past behaviour and habit attenuate the effects of intentions and implicit alcohol identity on HED.