At the Shrine of the Sacred Heart in Columbia Heights, where more than 1,000 first- and second-generation Hispanics attend Roman Catholic mass on Sundays, Spanish-language posters for adult religion classes are taped to the front of the church, hang from a sidewalk table on 16th Street and appear in the church bulletin.

Three miles north in Bethesda, the only sign that Our Lady of Lourdes has 300 Hispanics among its 2,968 members is a single announcement, among others on the glassed-in outdoor board, for the weekly Spanish mass.

Hispanics are the fastest-growing segment of the U.S. Catholic church -- as many as one-third of the 53 million American Catholics. At a time when other U.S. Catholics -- Irish, German, Italian, Polish -- have been absorbed into the mainstream, Hispanics are challenging them to remember what it was like to be poor and uneducated -- and devout in an old-fashioned way.

Anglos, caught up in their own evolution as participants in their parishes, have listened halfheartedly, some Catholic leaders say, and the church has responded by fits and starts.

"American Catholics have become too mainstream, too wealthy," said Bishop Alvaro Corrada, a Puerto Rican assigned to Hispanics in the Washington archdiocese, which includes the District and five Maryland counties. Corrada said he believes it is healthy that "Hispanics are making demands for new rituals . . . and more social action."

Pope John Paul II carries a similar message this week to the South and Southwest, and Hispanic Catholics there are expected to receive him enthusiastically. But Hispanic leaders say such devotion does not extend necessarily to the institutional church.

While mainstream Catholics have been raised in the northern European model of "pay, pray and obey," a 1985 study of Hispanic Catholics by the Northeast Catholic Pastoral Center indicates that, so far, most do not attend mass regularly or contribute money to the church, centering their faith in their homes and families.

"God is in our homes," said the Rev. Vicente O. Lopez, associate director of Hispanic affairs for the Catholic bishops' conference. "He's on our walls and in the sayings we use."

Among recent immigrants, language may contribute to sparse participation. And an estimated 22 percent of U.S. Hispanics live below the poverty line, so many may be preoccupied with finding or holding jobs.

Originally inclined to let Hispanics find the church on their own, American Catholic officials have recently stepped up efforts to draw them in, partly because fundamentalist Protestants are seeking out the same group. The center study said that 80 percent of Hispanics who responded said they had been approached by evangelical Protestants.

In Washington and northern Virginia, the number of Catholic services in Spanish has risen from five in 1972 to 23. Washington Archbishop James A. Hickey recruited Corrada, one of 19 Hispanic bishops in the country, in 1985 and has appealed for funds for the Hispanic Catholic Center in northwest Washington. Last year, the center found jobs, housing, food or legal assistance for 25,000 Hispanics, 68 a day.

Hispanics belong to parishes in greater numbers in the inner city. At Sacred Heart, for example, the share of Hispanic members is 45 percent and growing. At Lourdes in the suburbs, Hispanic membership has held at 10 percent for the last few years. Community organizers estimate that about 250,000 Hispanics live in the Washington area and as many as 95 percent of them are Catholic.

Our Lady of Lourdes has had four Spanish-speaking assistant priests in the last five years. Without consistent leadership, programs have faltered, according to Gustavo Gatti, a Paraguayan and one of two Spanish-speaking members on Lourdes' 14-member parish council.

The Rev. William O'Donnell, pastor of Lourdes since the early 1980s, says the church must provide Spanish-speaking programs and priests now, but "in a generation or two, they'll experience the same kind of integration as we Irish did."

In three years at Sacred Heart, the Rev. Stephen Carter says he has seen a "huge gap in culture widened by language and fear." Each Sunday, immigrants from one of the countries represented in the parish sponsor a special mass and feast after to show parishioners who they are.

Sacred Heart began as the place of worship for successive waves of immigrant Irish, American blacks and most recently, Haitians and Hispanics. Rosa Maria Eubanks, a Mexican-American member of the church, says she heard not long ago that several non-Hispanic parishioners among the church's 6,900 members were complaining that the church "wasn't theirs anymore, and they were going to leave and take their money with them." There was no exodus, she said, but added, "It takes a long time to accept a new member of the family."

The Hispanic identification of church with family is a model for the Catholic "base community," which originated in Central America where priests are scarce and lay Catholics have formed small groups to practice their religion and take care of each others' earthly needs.

The idea is taking hold now in the American Southwest, where priests are in shorter supply than in the East. Its supporters say it could help bridge the gap elsewhere between independent, mainstream Catholics -- whom the pope is urging to take their faith into their communities -- and Hispanics -- whom he is urging to take more leadership.

"We tend to take care of the class that has already made it," says the Rev. Patrico Guillen, a pastor from Riverside, Calif., who has set up 21 small "base communities." "If we're not careful, we will become like the European church, and lose the poor blacks, the poor Anglos, the poor Asians, the poor Hispanics."