In a questionnaire study, 51 Taiwanese college students were asked to judge 48 natural and human-made hazards on nine risk characteristics. Another group of 61 students were asked to rate the magnitude of 80 hazards and their attitudes toward these hazards. To evaluate the dimensionality of risk perception, participants' ratings for the nine risk characteristics were analyzed using Profile Analysis via Multidimensional Scaling approach. Two dimensions of risk perception were identified: (i) Involuntary versus Immediate Effect; and (ii) Delayed Effect versus Known to Science and Chronic. The relationships of risk perceptions and perceived public and private responsibilities in risk management were examined. Catastrophic, certain-to-be-fatal, dreaded, and uncontrollable risks were perceived as more deserving of public risk management, while controllable risks that were known to science, known to those exposed, and chronic were perceived as more deserving of private management. In particular, diseases are perceived as most deserving of private risk management and least deserving of public risk management; and technologies are perceived as most deserving of public risk management and least deserving of private risk management.