CATONSVILLE, Md. — Cardinal William Keeler, who helped ease tensions between Catholics and Jews and headed the oldest Roman Catholic diocese in the U.S. for 18 years, died Thursday. He was 86.

Archbishop William Lori announced in a statement that Keeler died at St. Martin’s Home for the Aged in Catonsville. No cause of death was released.

Keeler retired in 2007 as the head of the archdiocese of Baltimore.

He devoted much of his clerical life to improving ties with other denominations, especially Jews. From 1992 to 1995, he was president of the National Conference of Catholic Bishops. He also served as moderator for Catholic/Jewish Relations and was a member of the Committee on Ecumenical and Interreligious Affairs.

In a 1993 interview, Keeler said he developed his strong ecumenical bent while attending summer camp as a boy with Protestants and Jews. The experience, Keeler said, offered him “many opportunities to work with people from other churches and to engage in a kind of informal dialogue with them, to see their goodness and their interest in things that were good.”

Keeler was a priest for 37 years and served as an expert adviser to Pope John XXIII at the reforming Second Vatican Council of 1962-65.

He took over the Baltimore Archdiocese in 1989 after serving as bishop of Harrisburg, Pennsylvania. He was elevated to cardinal on Nov. 26, 1994.

Keeler said he chose the priesthood as a way to thank God.

“I thought, ‘The Lord has blessed me, and how can I say thanks and what would be the best way?’ And it got clearer and clearer that this is what I should do,” he said.

Keeler was born in San Antonio, Texas, and grew up in Lebanon, Pennsylvania. He attended St. Charles Seminary at Overbrook in Philadelphia, where he received a bachelor’s degree in 1952. He received a degree in sacred theology from Pontifical Gregorian University in Rome in 1956 and a doctorate in canon law in 1961. He was ordained on July 17, 1955.

As president of the National Conference of Catholic Bishops, it was Keeler’s job to keep conference business moving but also to mediate potentially divisive issues, such as the role of women in the church and the celibacy of priests.

Perhaps the high point of Keeler’s career was Oct. 8, 1995, when Pope John Paul II visited Baltimore. The pope led a Mass for 50,000 people at the Baltimore Orioles’ stadium.