Background: The aim of the current study is to understand Americans’ attitudes toward deceased organ donation and to assess their level of acceptance on positions toward organ donation. Methods: In summer and winter of 2023, 2 national samples completed measures of attitudes toward donation, reported their registration status, rated positions related to donation, and provided demographic information. Results: Data from 2 samples indicated registration estimates between 50% and 57% and a significant proportion of those unregistered reported reluctance to register. The believability of national registry estimates and ratings of acceptability of 9 organ donation positions differed by registration status. Conclusion: Mass media and motor vehicles interventions seeking to increase registration rates should take into consideration individual attitudes and support toward donation may not be as strong as once thought.