The research reported here considers the role of attitudes, norms and control in transport mode choice, specifically attempts to reduce car use through individualised marketing campaigns. Much work to reduce car use focuses on the provision of information. Often, this information is concerned with persuading people of the need to reduce car use, and increasing their awareness of the alternatives available. It is hoped that the information provided will change individuals’ attitudes towards car use and the use of alternatives, and thus cause them to reduce their car use (i.e., change their behaviour). The most sophisticated projects will tailor information so that it is personally relevant to individuals and specific journeys for which it is feasible to use an alternative to the car. Few projects are explicitly structured around a theory of behaviour or how to change behaviour, although the idea that attitudes are fundamental is often implicit. That is to say, the idea that to change behaviour, you need to change attitudes is central. However, theories of behaviour, e.g. Ajzen’s Theory of Planned Behaviour (TPB), indicate that other factors in addition to attitudes inform behaviour. The TPB suggests that behaviour is in fact the result of relevant intentions, and is not directly influenced by attitudes. The TPB suggests that these intentions are formed from a combination of attitudes, subjective norms and perceived behavioural control (PBC). Research that specifically tested the TPB in relation to reducing car use, supports the idea that PBC and norms can be significant in relation to reducing car use. Additionally, the research suggested that attitudes were not always significant to actual change when the fact that car use has negative impacts is already accepted. The results of the research are presented and the consequences for TPB operationalisation in the context of reducing car use are discussed. The potential role of personal norms is also considered.