Policy and practices for evaluating people with disabilities in Taiwan have changed extensively over the past 100 years. This study first traces the changes in the disability evaluation system and the medicalization of disability in Taiwan. Then this study tries to answer three main questions: What is disability? Why is disability evaluation needed? Why it is mainly based on medical examination? The concepts of disabled role, administrative category, and needy group are used to explain the use and limit of the medical examination of impairment. This study concludes by discussing the implications for the new disability assessment system in Taiwan.