Nonsectarian, in its most literal sense, refers to a lack of sectarianism. The term is also more narrowly used to describe private educational institutions or other organizations not affiliated with or restricted to a particular religious denomination.

Examples of private universities that identify themselves as nonsectarian include Cornell University, New York University, Ohio Wesleyan University, Syracuse University, Kwansei Gakuin University, Howard University, George Washington University, Brandeis University, Duke University, Reed College in Oregon, Tulane University, Northwestern University, and Rice University. Private primary and secondary schools also self-identified as nonsectarian include Columbia Grammar & Preparatory School in New York (the oldest nonsectarian school in the U.S.), Friends School Mullica Hill in New Jersey, as well as The Pembroke Hill School and George Gordon School of Law in Missouri.

Organizations that are explicitly nonsectarian include the Apex Clubs of Australia, those participating in the Ethical Culture Movement, International Society for Krishna Consciousness, the National Jewish Medical and Research Center, and the Tibetan Buddhist Center of Philadelphia.

In Northern Ireland, nonsectarian refers to groups identifying themselves as neither Nationalist/Republican or Unionist/Loyalist, such as the Alliance Party of Northern Ireland.