Background: If a clinician has to make decisions on diagnosis and treatment, he or she is confronted with a variety of causal theories. In order to compare these theories a neutral terminology and notational system is needed. The Causal Modelling framework involving three levels of description--biological, cognitive and behavioural--has previously been used to compare causal accounts for dyslexia and autism. Method: In this article we present this framework and explore its application to four causal theories of conduct disorder. We discuss the problems we encountered in this application and evaluate both the framework and the theories of conduct disorder. Conclusions: It was possible to capture parts of the theories of conduct disorder in the Causal Modelling framework but a multi-model approach may be necessary for the alternative theories of conduct disorder we evaluate. The application of the framework helps to see the relationships among the various theories of aspects of conduct disorder and demonstrates the need for more explicitness in the causal theories.