It was 1963, the week of Lent and a time of racial strife in Maryland when Archbishop Lawrence J. Sheham of Baltimore issued an unequivocal pastoral letter attacking Catholic lawmakers who had rejected a public accommodations bill. Since Catholics historically had suffered discrimination, he wrote, "we have a special obligation to place ourselves in the forefront of movements to remove the injustices and discriminations which still remain."

The parochial schools already had been integrated in Baltimore and, at the direction of Washington Archbishop Patrick A. O'Boyle, in the District's Maryland suburbs and in Southern Maryland. When several small schools were closed and a new central one opened, integration came in 1956 to St. Mary's County, a Catholic stronghold south of Washington.

"When O'Boyle put the word out, it was integrated without any brouhaha," said Thomas Spaulding, 69, a deacon at Our Lady's Church, in Medley's Neck near Leonardtown.

A commitment to social justice and equality, sometimes with an accompanying ecclesiastical nudge, characterizes much of the long history of Catholicism in Maryland, a state whose earliest colonial roots were planted by English Roman Catholics seeking a place to worship in peace.

The scheduled visit of Pope John Paul II to Baltimore on Oct. 8 is the first ever by the head of Roman Catholicism to that city. It also will bring him to the seat of the first diocese and archdiocese in the United States, established in 1789 and 1808, respectively, and which, until recent decades, included the District and Southern Maryland.

The papal visit to Baltimore further serves to underscore the intertwined history of Maryland and Catholicism in the United States, one that has influenced the border state's tradition of social tolerance and political moderation on most matters. Among scholars, Catholicism in Maryland not only has its own distinct flavor but it also has a name: the Maryland Catholic tradition.

"There is something aristocratic or elitist about the Maryland Catholic tradition," said Robert Brugger, history editor of the Johns Hopkins University Press and publications chairman of the Maryland Historical Society. "It has a lot to do with leadership of the better born, the well-to-do, the well-educated who are themselves striving to be assimilated, who want to belong. Nonetheless, because it tries to make the church work as an American institution, it helps to pull people toward the center."

The tradition persists, and the state's 800,000 Catholics today make up about 20 percent of Maryland's total population, ranking it in the middle of the states. Proportionally, the Catholic population hasn't changed much in the last several decades, officials say, but much of it has migrated in recent years from the cities to the suburbs and beyond.

The demographic shifts are emblematic of those occurring throughout the general population and in other large metropolitan areas, leading to some consolidation and reallocation of church resources, to contracting in the city and expanding in the suburbs.

The Baltimore Archdiocese has contracted from its earliest days. It now encompasses only the city and eight central and western Maryland counties, with 56 percent of Maryland's Catholics. The District and Southern Maryland were broken off in 1939 to form the Washington Archdiocese, accounting for 42 percent of the state's Catholics.

The first Catholic settlers -- English gentlemen, some with families; a few artisans, laborers and indentured servants; and a Jesuit priest -- arrived in 1634 to found a proprietary colony.

With Father Andrew White, the 200 or so colonists celebrated the first Mass in the English New World on St. Clement's Island in the Potomac River on March 25, 1634 (the date is still a state holiday, designated Maryland Day), and they built the first Catholic chapels in the colonial capital of St. Mary's City.

They went on to pass the first law in America for religious freedom, the 1649 Act of Toleration, only to lose their own freedom of religion decades later when intolerant rulers came to power in England. Their colonial counterparts quickly moved the capital to Annapolis and enacted a series of discriminatory laws.

Catholics were barred from voting, practicing law and holding public office. They were forbidden to worship in churches or to make converts. Catholic landowners were required to pay double taxes.

But Maryland Catholics and Protestants found common cause in the War for Independence, and Charles Carroll, of Carrollton, was a Maryland signer of the Declaration of Independence. His cousin, John Carroll, of Upper Marlboro, was the first American bishop (and later archbishop) and founder of the first Catholic college in America, Georgetown. Archbishop Carroll High School in the District is named for him.

On matters of race in the 19th century, Maryland Catholics largely reflected their region. The official antebellum church position was "to mitigate the condition of slavery," not to abolish the institution, Catholic historian Thomas W. Spaulding has written. Many Catholics fought for the Confederacy; others for the Union.

In Catholic Southern Maryland, Jesuit priests actively had converted black slaves to Catholicism, the faith to which their descendants still hold. There, blacks and whites mostly worshiped in the same churches, though they sat separately.

St. Mary's was for Catholics, and remains, at least in name, Maryland's "Mother County." A priestly "blessing of the fleet" occurs each October on the Potomac off St. Clement's Island, now nearly treeless and largely eroded but still with its landmark cross.

In the 19th and early 20th centuries, Baltimore became a magnet for Catholic immigrants from Europe. Ethnic neighborhoods of Italians, Polish, Germans, Irish and others formed with the parish church the focal point. At the same time, St. Francis Xavier, the oldest Catholic church in the United States with an all-black population, was founded in Baltimore in 1864.

In the Washington area, Catholic schools have been expanding in recent years in Montgomery and Prince George's counties, and in Frederick, where ground was broken recently on a 450-family church in Middletown to serve a swelling population of families that have moved to suburbia.

Parishes in the Baltimore suburbs also have experienced growth stemming from middle-class flight. The demographic shift has seen the city's Catholic population plummet from a peak of 150,000 half a century ago to 33,000 today, but with almost as many churches, 57, three-fourths of them built before 1940.

"If a church is burying 35, marrying two and baptizing one, the trend is very evident," said archdiocese spokesman Bill Blaul.

The economics of demographic change forced the archdiocese last year to consolidate parish operations, "twinning" 14 weaker churches with 14 stronger ones to share financial resources and, in some cases, priests.

Among those linked are St. Stanislaus Kostka, with an aged and dwindling population in the Fells Point area of East Baltimore, and St. Casimir's, another Polish American parish but with more parishioners in the nearby Canton neighborhood.

"Basically, at least 75 percent {of his parishioners} are over 70 years old," said the Rev. Maurice Piszcatowski, of "St. Stan's." "Of course, the children aren't living in the city; they're living in the suburbs, mostly northeast of Baltimore. Twinning has to work. There is no choice."

The church, however, remains influential in political life in Maryland.

In 1987, for example, the Maryland Catholic Conference succeeded in abolishing the death penalty for minors in Maryland.

To promote the Catholic agenda in Annapolis, the bishops of Washington, Baltimore and Wilmington, Del., meet every year before the General Assembly with the governor, much like bankers, beer distributors or any other special interest group.

What concerns the Catholic Church in Maryland is a wide range of issues on which it often takes a liberal stand. Although it opposes executions, it is for progressive taxation and a host of health and welfare programs for the poor, minorities and migrant workers. The church also opposes legislation to legalize assisted suicides. It supports living wills.

Its position on gambling is cautiously moderate -- it opposes casinos but condones bingo, a revenue source for some parishes -- and it is unalterably opposed to abortion. "It seems to me that {abortion is} the only issue that most gets talked about when the matter of church involvement in public policy is discussed," said Richard J. Dowling, executive director of the conference, "and that's regrettable." CAPTION: Jean Williams, her son, Derek Williams, and his son, Taij, represent three generations of parishioners at Baltimore's St. Francis Xavier, America's oldest all-black Catholic church. CAPTION: A young parishioner and ladies' auxiliary members wait outside Baltimore's St. Francis Xavier, the oldest all-black Catholic church in the United States. CAPTION: A statue of John Carroll, the United States' first bishop, at Georgetown University, which he founded.