Context-Limited studies, particularly in Australia, are aimed at understanding young people's beliefs about organ donation. Identification of such beliefs may serve to increase donation decision registration and decision discussion rates among this age cohort. Objectives-To examine young adults' knowledge about organ donation and to use a theory of planned behavior framework to determine the differences in behavioral, normative, and control beliefs between young adults who had and those who had not registered and discussed their organ donation decision with family or significant others. Participants-Australian university students (N=233) completed a questionnaire assessing knowledge about the organ donation process and beliefs related to organ donation decision registration and decision discussion. Results-Young adults demonstrated knowledge deficits about the support of Western religious denominations for organ donation and the circumstances surrounding donation. Unregistered donors were more likely to focus on the costs of registering; however, no belief-based differences for decision discussion emerged. Young adults who had registered and discussed their decision were more likely to believe that family members and friends thought they should do so. Lack of motivation was reported as preventing registering and discussing, and uncertainty about how and when to raise the topic prevented young adults discussing their donation decision. Conclusions-Understanding of young adults' knowledge and beliefs enables the development of strategies encouraging donation decision registration and donation decision discussion with family or significant others, thereby increasing the likelihood that the donor's wishes will be carried out.