失能為所有現代國家主要的社會風險之一，但其原因不僅因職業災害而來，普通傷害所導致的失能問題亦使勞工及其家庭陷入經濟不安全的困境之中。由於失能期間沒有工作所得又需支付額外的醫療、設備等花費，故各國所發展出的相關保障制度同時注重該期間的現金給付、實物給付以及助其早日重回生產性工作之醫療照顧、就業促進與職業重建等福利服務。 以當前世界主要國家美國為例，於1935年通過社會安全法案，並在1956年通過失能給付，將絕大多數的勞工納入的老年、遺屬與遺屬保險（Old-Age, Survivors, and Disability Insurance；OASDI）體系之中，1983年更將公務員納入其中。除給予失能勞工及其依附者失能現金給付與所需之醫療給付外，並透過就業促進與職業訓練等相關制度，促使獲給付者早日重回生產性工作，為一生生不息的制度。儘管其制度不若德國實施百餘年之制度來得完善與全面，但已具有相當之規模，且符合世界之公約數。 我國則依照公務人員、軍人、勞工與農民等四群體制訂各自之相關保險給付制度及其退休撫卹制度中，而勞工與農民所享有的保障則極度不平等；目前交付三讀中的國民年金法草案將涵蓋其他國民之相關社會風險。我國目前在一次給付、失能之定義、失能之判定機制、職業重建服務、就業促進等眾多機制上皆顯不足或欠缺，在在背離了各國社會保險制度之公約數，無法給予勞工所需之保護，應立即進行改革。 本研究主要採歷史制度比較法，先對美國之歷史、制度與問題進行瞭解後，再依其經驗找尋我國制度改革上所應依循之方向與應避免之問題。期望未來所建立的制度，除能給予失能勞工足夠的現金、實物給付以及福利服務外，並促進其重回職場，為整體社會之再生產繼續貢獻。 / Disability or invalidity is one of the main social risks in modern countries and has been recognized by almost all the countries since 1880’s. This kind of risk was paid much attention from the inclining of cases that labor got job-related impairments and made their families fall into miserable situations. Those bad conditions are not only caused by job-related impairments, but also ordinary ills and impairments in everyday life. For instance, a person who is hit by a car may be unable to work, and it makes his or her family in danger. Accordingly, this dissertation intend to deal with the issue concerning about the proper measurements of disability determining and protecting. For those people who are physically or psychologically impaired and unable to work temporarily or permanently, almost all the countries will provide all kinds of benefits they need through their Social Insurance programs, such as monthly cash benefits, medical care, vocational rehabilitation, job placement, job training programs and so on, and U.S. is one of thos e countries. Related schemes have been practiced in Taiwan since 1950, but there are many problems waiting for us to amend. For example, the unequal treatment between public servants and other people needs to be reformed. Furthermore, the definition of disability remains at the stage of compensations of impairments, the determination of disability is too loose, and the procedure of determination is too simple etc. The purpose of this dissertation is to get closer understanding of the OASDI of U.S., especially DI. Besides, it is expected to learn something from the case reviewed above and to establish a sound Social Security system in Taiwan, thus to prevent the problems that may occur in advance. In this sense, only to pursue the norms that are internationally share, we can make our society more adequate, equal, and safer than before.