This study analyzes the usefulness of an attitude-based target group approach in predicting the ecological impact of mobility behavior. Based on a survey of 1,991 inhabitants of three large German cities, constructs derived from an expanded version of the Theory of Planned Behavior were used to identify distinct attitude-based target groups. Five groups were identified, each representing a unique combination of attitudes, norms, and values. The groups differed significantly from each other with regard to travel-mode choice, distances traveled, and ecological impact. In comparison with segmentations based on sociodemographic and geographic factors, the predictive power of the attitude-based approach was higher, especially with regard to the use of private motorized modes of transportation. The opportunities and limits of reducing the ecological impact of mobility behavior on the basis of an attitude-based target group approach are discussed.