美國1935 年開辦「老年、遺屬及障礙保險」（Old Age, Survivors, Disability Insurance，簡稱OASDI）公共年金方案，至今已成為該國最具規模的福利方案。然而，自1980 年代以來，OASDI 方案卻出現福利資源分配缺乏世代公平的爭論。本文旨在以OASDI 方案為例，探討此世代公平爭論之源起、意涵、評估限制，以及改革對策。研究發現：（1）OASDI 提供早期退休者優渥給付，造成龐大年金債務並開啟世代公平之爭議；（2）世代公平常被混淆且評估困難，因受限於移轉管道複雜、給付樣貌多元、私人雙向移轉、先前世代貢獻；（3）OASDI 可藉由建立自動平衡措施來改善年金財務；（4）美國改革對台灣年金保險體系的啟示包括：年金制度應整合各職業身份、年金改革應與時俱進、勞保年金存在世代不公現象。

The Social Security Act in 1935 regulated the OASDI (the Old Age, Survivors, Disability Insurance) pension scheme, which has become the most influential welfare regulation in the Unite Sates. However, this scheme has caused a debate in intergenerational equity since 1980s. This paper takes the example of the OASDI, reviewing the debate of intergenerational equity in respect of the origins, definition, assessment limitations, and the reform strategies for long-term solvent about the OASDI in the U.S. Our research findings are as follows: 1. In the U.S., the OASDI providing the generous benefits for the elderly, which are the major causes for intergenerational equity debate. 2. It is apparent that the intergenerational equity debate has been ill-served by ambiguity and difficulty for assessment. The limitations include: the ways for transfers are complex; types of benefit are various; two ways for private transfers; previous generations’ contributions. 3. For reforming pension, it is valuable for the U.S. to establish a self-balancing mechanism. 4. This paper identifies the many lessons that the U.S.’s experiences can offer Taiwan’s pension system and that concern, most notably, unify the existing occupational pension/ social allowance schemes, the pensions reform shall not be delay, and there is a phenomenon of intergenerational equity in Labor Insurance.