Born in New Haven, Connecticut on February 13, 1935, Bishop Rosazza is the eldest child of the late Agatha (Dinneen) and Aldo Rosazza. He grew up in Torrington and attended St. Francis Elementary School and Torrington High School graduating in 1952. After one year at Dartmouth College he entered St. Thomas Seminary in Bloomfield, Connecticut. Next he studied at St. Bernard Seminary in Rochester, New York, and completed his four-year concentration in theology at Seminare Saint-Sulpice in Paris, France. He was ordained a priest for the Archdiocese of Hartford in Notre Dame Cathedral in Paris on June 29, 1961.
Back in Connecticut he served as assistant pastor in the Church of St. Timothy in West Hartford and then was appointed to the faculty of St. Thomas Seminary where he taught French, Spanish and Italian.
In 1972 he became co-paster of Sacred Heart Church in Hartford's north end, the mother church of Hartford's Hispanic Catholic community. In 1978 he was named auxiliary bishop to the Archbishop of Hartford by Pope Paul VI and was ordained bishop on June 24. He continued to minister at Sacred Heart until his transfer to Waterbury in 1981. In 1988 he was assigned to New Haven and resides on the grounds of the Hospital of St. Raphael.
On February 2, 1997, Archbishop Cronin appointed him Episcopal Vicar for the Spanish speaking Catholics in the Archdiocese of Hartford.
He is a member of the National Conference of Catholic Bishops' Committee for Social Development and World Peace and is liaison with Brazilian Catholics for the Committee on Migration and Refugees. He is also bishop advisor to the National Catholic Student Coalition. He is one of the founders of the Naugatuck Valley Project, a coalition of churches and labor union locals as well as ECCO (Elm City Congregations Organized), a community organization of 18 churches in the New Haven area. Also, he is one of the five bishops who drafted the U.S. Catholic Bishops' Pastoral Letter on the U.S. Economy and Catholic Social Teaching.