Washington National Cathedral and Boston's Trinity Church, Copley Square share several characteristics. Both are preeminent houses of worship in the Episcopal Church, both have distinctive architectural features and illustrious histories and both draw large interfaith crowds for public celebration and mourning.

There's one prominent difference, though, aside from one's location in the heart of Boston and the other's on one of the highest points in the District. Trinity Church is an inner-city parish with a mandate to serve its congregation and the increasingly diverse community around it. Washington National Cathedral has no congregation per se and has a mandate to serve a much wider community -- one that includes the District's poorest neighborhoods and the country's highest-ranking officials.

Early next year, the Rev. Samuel T. Lloyd III will begin exploring how much alike -- and different -- the two churches are when he leaves Trinity and assumes the position of the cathedral's 10th dean.

"It's a profound honor and a daunting challenge to come to a significant church such as this," Lloyd, 54, said this week in a telephone interview. "I come eager to discover the life that's already there, to honor what has grown out of the cathedral's life and ministry in the last years and to ask the question where God is calling the cathedral next."

Lloyd succeeds the Rev. Nathan D. Baxter, who unexpectedly announced his resignation in January 2003, effective in June of that year. Lloyd will begin his job early next year, but the date of his installation has not been decided.

The Rev. John B. Chane, consecrated as bishop of Washington two years ago and formerly dean of St. Paul's Cathedral in San Diego, served as dean of the cathedral while a 17-member national committee searched for a full-time replacement. The committee, consisting of clergy and laity from across the country, considered about 50 applicants and could have recommended several candidates from whom Chane would choose the dean.

It presented one name, and Chane announced Lloyd's appointment last week.

"Sam Lloyd is a very fine preacher with a proven track record as leader of one of the most prestigious congregations in the United States, at least in the life of the Episcopal Church," the bishop said in an interview. "It takes a unique talent to become dean of this cathedral, and Sam has all the gifts" to fulfill a mission envisioned a century ago and take it into the future.

The Rev. Frank T. Griswold, presiding bishop of the Episcopal Church, said he was delighted with the appointment and called Lloyd "one of the most gifted clergy I know."

The cathedral's mission, stated in an 1893 charter that was passed by an act of Congress, involves being "a great church for national purposes," a "house of prayer for all people" and the "mission of the Episcopal Diocese of Washington."

The mission has expanded as the national and global communities have experienced traumatic upheavals, Chane said. Today, the cathedral is known not only as a place to celebrate presidents' inaugurations and mourn the deaths of heads of state, but also for its role in interfaith and intrafaith dialogue, the bishop said.

Parishioners at Trinity Church in Boston said that they were saddened when they heard of Lloyd's imminent departure but that they share in the joy of his appointment to one of the country's most visible and prestigious pulpits.

Joan Hadly, a member of the vestry who joined Trinity nine years ago, said Lloyd announced his plans at a vestry meeting last week -- a gathering that turned emotional. "I told Sam as I hugged him, with tears in my eyes, how grateful I was for his ministry with us and that I would continue to uphold him in prayer, because I felt it definitely was the call of God I felt, too."

Hadly said what impressed her the most about Lloyd was that "he lives his life according to what he preaches and teaches."

"If I had to pick out of everything Sam tried to teach, it was how to live the great commandments to 'love the Lord our God' and 'our neighbors as ourselves,' " she said.

The most dramatic change since Lloyd came to Trinity in 1993 has been the increased membership of families who have young children, said Albert G. Mulley Jr., Trinity's senior warden and a member since 1981.

Trinity has long been a strong congregation, with more than 1,000 people attending Sunday services. But the makeup of the membership has changed from mostly single or widowed adults older than 40, and now includes families coming from the city, the suburbs and as far away as Cape Cod and New Hampshire.

A decade ago, Trinity had "only a handful" of children in its church school, Mulley said. Today, "well over 200 kids" attend the church, which has "a very large and robust teen ministry," many of them disadvantaged children who joined as a result of Trinity's community outreach programs, he said.

Lloyd also guided the parish's $53 million capital campaign to dig out and renovate space beneath the church, which was designed by renowned architect H.H. Richardson and completed in 1877. The new educational and meeting facilities are scheduled to open in January.

A cathedral is so named because it houses a cathedra, or bishop's chair, and is the center of ecclesiastical authority. Traditionally, bishops held the position of cathedral dean, a term associated with teaching and learning. But the expansive nature of the modern church has made the dual roles impractical, said Chane, 60, who oversees a diocese with 92 congregations and 42,000 members in the District and Charles, Montgomery, Prince George's and St. Mary's counties in Maryland.

The job of dean of Washington National Cathedral, officially known as the Cathedral Church of St. Peter and St. Paul, is monumental. Lloyd will oversee an annual operating budget of more than $16 million, a 200-person staff, more than 1,100 volunteers and all programming and worship at the cathedral -- including six daily services, seven Sunday services, and numerous concerts and special events throughout the year.

In addition, the dean is vice chairman of the board of trustees of the Protestant Episcopal Cathedral Foundation, which governs the cathedral and four schools on its 57-acre grounds: the National Cathedral School for Girls; St. Alban's School for Boys; Beauvoir, the National Cathedral Elementary School; and the recently formed Cathedral College, a continuing education center. And the dean oversees such community-directed services as public school mentoring programs and participation in the local Habitat for Humanity program.

Baxter, Lloyd's predecessor, said he "enjoyed immensely" the 12 years he served as dean, but he added that the task of running "an organization as complicated as the cathedral" was exhausting.

Since October, Baxter, 56, has been rector of the 1,300-member St. James Episcopal Church in Lancaster, Pa., the area in which he grew up, was ordained and served his first parish.

"I'm enjoying being a pastor again," Baxter said in an interview from Lancaster. He also is professor of ministry at Lancaster Theological Seminary and is writing a chapter for a book, "God and Country: Diverse Perspectives on Christianity and Patriotism."

Lloyd, a native of Canton, Miss., also is experiencing a homecoming of sorts. As a personnel officer in the Air Force in the early 1970s, he was stationed at Cape Charles and in Washington.

After military service, he received a master's degree in English literature from Georgetown University and a doctorate in that field of study from the University of Virginia. In 1981, he received a master of divinity degree from Virginia Theological Seminary in Alexandria, and for three years he was an assistant rector in Charlottesville and assistant professor of religious studies at the university.

Lloyd said that he is aware of the complications of his new job and of life in Washington, and that he believes God has led him here.

"One of the expectations [of the job] is that the dean have a prophetic voice. I hope and pray I will be that," said Lloyd, who uses the standard lectionary of Scripture readings as the basis for addressing such issues as the war in Iraq, homosexuality and the broadening gap between the rich and poor.

"I also hope I will come at it in a way that foundations are laid carefully and the possibility of conversation always exists," Lloyd said, "and that how I get there from the [scriptural] text at hand will be clear to anyone who looks."

The Rev. Samuel T. Lloyd III, at Boston's Trinity Church, Copley Square, will become the dean of Washington National Cathedral. The inner-city Trinity Church, here being renovated last year, has a mandate to serve its congregation and its diverse community.