The acceptance of multiple-occupant modes of transportation such as buses and carpools is an important factor in energy conservation. Two experiments are reported which show how attitudes toward different modes of transportation are influenced by interpersonal factors. Experiment 1 showed that individuals perceive differences in the characteristics of people who use different modes and that these differences are related to their own transportation preferences. Experiment 2 showed that the sex of each potential rider and whether or not each rider is an acquaintance of the respondent are important factors in carpooling. The implications of such results to policy makers are discussed
