A questionnaire study was conducted with truck drivers to help understand driving and compliance behaviour using the theory of planned behaviour (TPB). Path analysis examined the ability of the TPB to explain the direct and indirect factors involved in self-reported driving behaviour and regulation compliance. Law abiding driving behaviour in trucks was related more to attitudes, subjective norms and intentions than perceived behavioural control. For compliance with UK truck regulations, perceived behavioural control had the largest direct effect. The differing results of the path analyses for driving behaviour and compliance behaviour suggest that any future interventions that may be targeted at improving either on-road behaviour or compliance with regulations would require different approaches.