We report the results of a representative random-sample telephone survey of the public's willingness to donate organs. Our goal was to identify differences within the public and target groups who might be receptive to educational efforts to increase donation. We distinguish differences in attitude and demographic characteristics in three groups: those committed to donation, those opposed, and those who might change their opinions with more specific information. While approval of donation is nearly universal, only about half of the public would donate a relative's organs when they do not know the relative's preference. Whites, higher-income individuals, and those with higher educational levels were more favorable. Those who might change their minds fall midway between those committed and those opposed, both demographically and by attitude. They include more nonwhites and more individuals with incomes less than $25,000 than members of the group committed to donation. Targeting public education messages to this group is likely to have the most success in reducing the gap between supply and demand for human organs.