This dissertation discusses the political dimensions of scientific practice in Taiwan from two perspectives: the social contingencies of scientific knowledge and the role of government in medical science. The history of Taiwanese hepatitis B control program from 1980 to 1993 provides a valuable case study to investigate these issues. The controversies over the safety of the hepatitis B plasma vaccine display the social contingency of scientific knowledge. On the basis of different concerns or political interests, numerous participants joined the scientists in interactively shaping and reshaping the vaccine safety. When participants used various strategies and contradictory scientific knowledge to argue against each other, the credibility of experts and their scientific knowledge was downgraded, which in tum prevented scientific knowledge from serving as the sole arbitrator of resolving the controversies. The socially contingent characteristics of scientific knowledge provided a space for government agencies participating in shaping scientific knowledge formation. This historical case displays how the Taiwanese government significantly influenced the scientific knowledge formation regarding hepatitis B control in Taiwan. The government designed science policy to promote hepatitis B control, and government officials were involved in resolving the controversies over the safety of the hepatitis B plasma vaccine. Government scientists not only gave government agencies a certain degree of interpretative authority in the controversies, but also produced alternative scientific knowledge to support the government's science policy. When the government policy changed in response to social problems, the scientific knowledge regarding hepatitis B control also changed. This dissertation concludes by calling for more attention toward studying the role of government in scientific practice. Without considering how the Taiwanese government participated in the hepatitis B control program, our understanding about the formation and change of scientific knowledge regarding hepatitis B control would be incomplete. / Ph. D.