The Legal Case Files series documents the ACLU's involvement in litigation, ranging from files collected on cases for research purposes to records of cases they were significantly involved in. The records include documents filed with the court, correspondence, lawyer's notes, depositions and expert testimony, transcripts of the trials, newspaper clippings, and research materials on the background of the cases and legal precedents.

The Organizational Matters series documents the administration of the ACLU National Office and their interactions with the regional offices, affiliates, outside organizations, and the general public. The records include committee meeting minutes and mailings, staff files, and department records. The majority of the records are the files of Executive Director Ira Glasser and the records of the Legal Department.

The Printed and Audiovisual Materials series contains the published works of the ACLU, including publications, audio recordings, and videos. These include educational materials published by the ACLU, newsletters, press releases, and public appearances and interviews with ACLU staff.

The Project Files series contains the records of twelve of the ACLU's projects, which each addressed an area of civil liberties violations. Project records typically consist of case files, research files, and project publicity and correspondence. The best documented projects are the Children's Rights Project and Women's Rights Project, and to a lesser extent the Arts Censorship Project, Capital Punishment Project, and Reproductive Freedom Project.

The Regional Offices series documents the work and administration of the ACLU's three regional offices: Mountain States Regional Office, concerned with civil rights in the west and Native American rights, the Southern Regional Office, focusing on civil rights in the south, and the Washington, D.C. office, which concentrates on national legislation and the actions of the federal government. The files include correspondence, case files, office publications, research files, and the papers of individual staff members. Subgroup 3, Subseries 5B (Southern Regional Office) has been digitized and is 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.

Consists of drafts of, and material related to, American author Paul Blanshard's American Freedom and Catholic Power (1949)

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.

Ananda K. Coomaraswamy was a noted art historian and champion of Ceylonese and Indian culture. This collection covers a broad spectrum of Ananda K. Coomaraswamy's work in the fields of art history, philosophy, religion, and social criticism.

The Papers of Andrew C. Imbrie, Class of 1895, (1875-1965) provide information on his undergraduate years, his service as an alumni trustee from 1907 until 1912 (including a period as Financial Secretary of the Princeton University Board of Trustees (1909-1912) during which he had charge of reorganization of the business management of the University leading to the creation of what became the Office of the Controller) and his family's genealogy.