Congregationalist theological education was the motivation at the founding of Yale, and the professional school has its roots in a Theological Department established in 1822. The school had maintained its own campus, faculty, and degree program since 1869, and it has become more ecumenical beginning in the mid-19th century. Since the 1970s, it has been affiliated with the Episcopal Berkeley Divinity School and has housed the Institute of Sacred Music, which offers separate degree programs. In July 2017, a two-year process of formal affiliation was completed, with the addition of Andover Newton Seminary joining the school. Over 40 different denominations are represented at YDS.