Describes seven empirical studies which explore determinants of decisions to drive in the presence of alternative transport. Empirical chapters are presented as stand-alone papers. Study 1 uses qualitative methods to explore reasons for driving among commuters, which are subsequently quantified and tested as predictors in Study 2. Study 3 reports a meta-analysis of psychological correlates of car use, and Study 4 uses structural equation modelling to evaluate many of these as predictors of car travel. Studies 5-7 explore whether commuting mode choice should be seen as habitual behaviour.