Rev. Dr. Cecil Elwood Corbett ("Speaking Eagle") was born on the Cherokee Indian Reservation in Cherokee, North Carolina on March 4, 1931. He was the son of Frank Paul Corbett (1898-1966) and Phoebe Corbett (née Coleman; 1904-1958), a Choctaw Indigenous woman. Cecil was a member of the Nez Percé Tribe of Idaho. He attended elementary and high school in Pierre, South Dakota. He attended Wahpeton State School of Science (North Dakota State College of Science) and Cook Christian Training School (CCTS; Phoenix, Arizona campus) before receiving a Bachelor of Arts from Huron College in South Dakota in 1957. While attending CCTS, he met Irene Blatchford. The two married on December 29, 1951, and they were members of First Presbyterian Church in Kamiah, Idaho. Before entering seminary, Corbett served Ascension Presbyterian Church in Peever, South Dakota under the Board of National Missions for several months in 1955. During seminary, he worked as a student pastor at Bloomington Congregational Church in Bloomington, Wisconsin. He graduated from the University of Dubuque Theological Seminary in Iowa in 1962 and was ordained by Dakota Presbytery on September 7, 1961. He was awarded honorary Doctor of Divinity degrees by Huron College in 1968 and by Dubuque Theological Seminary in 1972.

After seminary, Corbett served First Presbyterian Church at Flandreau, South Dakota, where he worked among the Santee. In 1963, he received a call from the Pima First Presbyterian Church at Sacaton, Arizona to serve among the Pima on the Gila River Indian Reservation (Gila River Indian Community). Corbett became associate director for program of CCTS (Tempe, Arizona campus; later names include Charles Cook Theological School and Cook College and Theological School) in 1967, soon after becoming executive director in 1968. He served in that position until 1989, when he became chancellor. 

Corbett served the United Presbyterian Church in the U.S.A. (UPCUSA) and the Presbyterian Church (U.S.A.) (PC(USA)) in a variety of roles and functions. While serving as "Consultant for Ministries with Indians," he participated in the formation of the Consulting Panel on Ministries With Indians (part of the Council on Church Strategy and Development, Board of National Missions, UPCUSA) in 1970. The Panel brought together Presbyterian Church leaders from Native American communities to provide consultation regarding mission strategy in relation to the needs and opportunities of Native Americans. Variant names of the Panel include the Presbyterian Indian Consulting Panel, the Indian Consulting Panel, and the American Indian Consulting Panel. Around 1973, the Panel effectively became the Native American Consulting Committee (NACC) of the Program Agency. NACC was originally composed of five members from specific synods (synods of the Southwest, the Sun, Alaska-Northwest, Pacific, and Lakes and Prairies) and seven members at large.

Corbett's roles at CCTS and in NACC led to his participation in the establishment of the Native American Theological Education Consortium (NATEC; circa 1976). Created through the Presbyterian Church's Major Mission Fund, NATEC developed and trained Native Americans for ministry through Theological Education by Extension (TEE). The Consortium was originally comprised of CCTS, Huron College, and Dubuque Theological Seminary. Corbett also participated in the formation of the Native American Theological Association (NATA) in 1977, an ecumenical organization that functioned as an agency of Native American communities to facilitate the accreditation of related educational programs and of candidates for ordination through their respective denominations.

Additionally, Corbett was a member of the executive committee of the Council on Church and Race (COCAR; UPCUSA), field associate for the Board of National Missions (UPCUSA), and moderator of the Presbytery of Phoenix (1970). He held several titles and roles within the National Council of the Churches of Christ in the U.S.A. (NCCC), including chairperson of the National Indian Goals Committee.