Social Security—the American people’s most important insurance—does more to maintain living standards and prevent poverty than any other social welfare policy or program, public or private. This entry discusses why our nation’s Social Security system was built, what it does, how it evolved and how it continues to do so. Contemporary challenges and related policy options are identified regarding program financing and the public’s need for expanded protections—retirement, disability, survivorship, paid family leave, and paid sick leave, among other protections. The analysis highlights messaging and political strategies used by those seeking to diminish the role of Social Security and those seeking to expand its protections. The entry suggests that the values and objectives of the American Social Security system comport well with social-work; and that both opportunity and need exist for social workers to shape Social Security’s future through application of policy analysis, advocacy, organizing and administrative skills.