A behavioural science view is unfolded on sustainable development of society from a European perspective. Free-market expansion implies significant pressures on environmental and social qualities in many countries. An extended commons dilemma (ExCD) model is presented to capture the tension between individual and collective interests. A variety of people-environment studies can be well aligned with the successive ExCD steps. The model is applied to the expanding domain of motorised transport. Here, market-stimulated individual freedom is insufficiently checked by government policies aimed at securing vital collective goods. Current (Dutch and EU) policy principles are criticised and a set of guidelines for sustainable transportation is advanced. In view of these and on the basis of Dutch survey research, we may question economic growth, work and income as overriding factors of future human well-being. Conclusions are drawn about comprehensive sustainability research, the structuring of people-environment studies, and the issue of ëpracticing theory versus theorising practiceí.