The American Civil Liberties Union (ACLU) is the pre-eminent civil liberties organization in the United States, utilizing litigation, lobbying, and public education to defend and preserve the individual rights and liberties guaranteed by the U.S. Constitution. These records document the administration and work of the ACLU's national office, regional offices, and legal projects, with particular emphasis on the areas of civil rights, children and women's rights, freedom of speech (and all First Amendment questions), and due process, among many others. The records include case files, correspondence, meeting minutes, research files, and files of staff members. Portions of the records (Subgroup 1; Subgroup 2, Series 2, 3, and 4; Subgroup 3, Subseries 5B) have been digitized and are available for members of the Princeton community to view here. To view the database from outside Princeton University, please see the Guide to the American Civil Liberties Union Records.

The ACLU is the preeminent civil liberties organization in the United States. These records document the work of their national office in the areas of civil rights, children and women's rights, freedom of speech (and all First Amendment questions), and due process, among many others, predominantly from 1970 to 2000.

The organization that became Americans United for Separation of Church and State was founded in 1947 to protect church-state separation and religious freedom, as well as to educate lawmakers, religious leaders, and the general public regarding Constitutional religious liberties. The records document the administration and issues of the organization from its founding and include correspondence, meeting materials, and publications.