After the Feb. 19 ceremony, Steenson will wear the accoutrements of a bishop, but will bear the title monsignor.
Based in Houston, the ordinariate will be a niche within the Catholic Church for theologically conservative Anglicans (including Episcopalians) who want to embrace Catholicism while continuing to pray and sing in the liturgical traditions of the Church of England.
"Nobody does public liturgy the way the English do," Steenson, 59, said last week from his offices at the University of St. Thomas in Houston, where he teaches early Christian thought.
He recalled fondly the "stunning beauty" of the Psalms he heard sung in his graduate days at Oxford University. Benedict established an ordinariate for British Anglicans last year.
About 1,400 American lay people and 55 clergy are now preparing to "swim the Tiber," Steenson said.
In the Philadelphia area, they include two priests and dozens of laity looking to create their own parishes within the ordinariate.
They are welcome to recite the Hours and sing the Evensong hymns of the Anglican tradition, Steenson said. But moving to the ordinariate demands full conversion to the Church of Rome.
"You leave Anglicanism behind in the sense that you become a member of the Catholic Church," Steenson said. "But it's the Anglican traditions that shaped you that you bring with you."
For those who convert, the word Anglican "ceases to be a noun," he said, "and becomes an adjective."
The immediate task before him centers on vetting applications from current and former Episcopal clergy. Most are married and want to be ordained Catholic priests.
Among them is the Rev. David Moyer, who succeeded Steenson as Good Shepherd's rector in 1989. Moyer said last week about 70 members of that traditionalist Anglo-Catholic parish also planned to convert.
A vocal critic of liberal trends in the Episcopal Church, such as gay and female ordination, Moyer made international headlines in 2002 when the Episcopal Bishop of Pennsylvania defrocked him. He was later ordained a bishop in the Traditional Anglican Communion, a small, breakaway affiliation of church conservatives.
The Rev. David Ousley, former rector of St. James the Less Episcopal Church in Philadelphia's Hunting Park section, said the 45 congregants at his independent Anglican Church of St. Michael the Archangel in Overbrook Farms were "moving in the direction of the ordinariate, but no decision has been made."
Most of Ousley's conservative members once were parishioners of St. James. In 2005, they lost a court battle to retain ownership of their parish campus after they left the Episcopal Church.
"Even those [congregants] not excited about the ordinariate are grateful to the Holy Father for making the overture to us," Ousley said.
He and Moyer, both 60, both married, and both grandfathers, have been notified by the Vatican there is no theological impediment to their ordination as Catholic priests.
Both must undergo a lengthy, case-by-case approval before that, however. Most Anglican clergy are married - a state that Rome still views as exceptional.
A licensed pilot who builds his own planes, Steenson grew up a "farm boy" in rural Alabama in the Evangelical Free Church of America, an offshoot of Swedish Lutheranism. Married after college, he was a sportswriter at a newspaper in the Chicago suburbs when he took a course in patristics - the study of the writings of the thinkers, such as St. Augustine, who shaped the early church.
He converted to Episcopalianism, entered seminary, and was ordained in 1980. His scholarly interests took him to Harvard Divinity School, then to Oxford's Christ Church for his doctorate.
But entry-level teaching jobs in patristics were few and paid "appallingly," he said. With a growing family to support, he entered parish ministry and, in 1983, was hired as curate at the traditionalist All Saints Episcopal Church in Wynnewood.
In 1985, he was chosen rector of Good Shepherd, but he grew impatient with the liberalism of the Diocese of Pennsylvania, which serves the Philadelphia area. Rather than engage in an "adversarial" relationship with the bishop, he made what he calls a "painful decision," departing in 1989 for the conservative Diocese of Fort Worth.
In 2005, he was made bishop of the Diocese of Rio Grande, which serves Albuquerque, N.M., but in 2007, he announced he was stepping down to join the Catholic Church. He was ordained a Catholic priest in 2009.
He declined to predict how large the ordinariate would become or how long it would last.
The Catholic Church views it as an "enduring" home for former Anglicans, he said. But with no sign that Rome is about to allow its clergy to marry, he does not know whether it will find enough priests in years to come to serve the children and grandchildren of those now crossing over.
Meanwhile, he is "totally absorbed" with vetting the Anglican clergy who want to become Catholic priests.
Those still bitter at the Episcopal Church's liberal turn will have to "leave their anger at the door," he said, "and learn to forgive what you left behind."
Contact staff writer David O'Reilly at 215-854-5723 or firstname.lastname@example.org.