The Chicago Theological Seminary (CTS) is a Christian ecumenical American seminary located in Chicago, Illinois, and is one of several seminaries historically affiliated with the United Church of Christ. It is the oldest institution of higher education in Chicago, originally established in 1855 under the direction of the abolitionist Stephen Peet and the Congregational Church (now the United Church of Christ) by charter of the Illinois legislature.

In addition to being a seminary of the United Church of Christ, CTS offers students coursework necessary to be ordained by the Metropolitan Community Church denomination. It was the first theological school to introduce the field education experience into a seminary curriculum, the first to create a distinct Department of Christian Sociology in an American theological school, and the first seminary to award a degree in divinity to a woman in the United States (Florence Fensham, 1902).