The power of two different theoretical frameworks, the theory of planned behaviour (expanded to include moral norm) and the driver behaviour questionnaire, to predict and explain drivers' speeding behaviour are compared and a combined model is suggested. One hundred and seventy-five test drivers, participating in a large-scale ISA-evaluation, answered a questionnaire in spring 2000. Based on the questionnaire data, logged speeding in autumn 2001 was predicted and LISREL-analysis was used for structural equation modelling. According to the results the two frameworks, alone or in combination, could explain between 38 and 53% of self-reported speeding and between 24 and 26% of logged speeding. A combination of the theory of planned behaviour and the driver behaviour questionnaire is presented and implications for the understanding of driver speed control are discussed.