A second parochial grade school will open in Loudoun County this month at a time of unprecedented growth in the Diocese of Arlington and what church and school officials say is a growing interest in Roman Catholic education.

About 150 kindergarten through eighth-grade students will begin classes at Our Lady of Hope Catholic School in Potomac Falls on Aug. 29.

The two-story, 11-classroom school, which includes a computer lab, a multipurpose room and an art and music room, could eventually house as many as 500 students. The school, which is on 12 acres, will have 18 faculty members, 10 of them full time. The students will come primarily from the Potomac Falls and Cascades areas of eastern Loudoun, but some will come from Ashburn and as far away as Leesburg and Purcellville, said the Rev. William P. Saunders, the parish priest.

Church officials say the Diocese of Arlington, which includes 21 counties and seven cities in Northern Virginia, is one of the five fastest-growing dioceses in the United States. Loudoun is the fastest-growing part of the diocese, with about 37,000 Catholics. The county has six parishes, and the diocese plans to create a new mission in South Riding.

The diocese opened its first Loudoun grade school, St. Theresa, in Ashburn in 1994, but it has reached its capacity. The diocese plans to build a high school in South Riding, and there are several Catholic schools in Loudoun run by lay people.

Our Lady of Hope principal Joseph Orandello said that about 18,000 students are enrolled in the diocese's schools and that enrollment is growing. He said more parents want to give their children an education based on Catholic values and morals.

"Based upon my conversations with parishioners in this parish, I believe there is a slow transition toward a more conservative Catholic elementary education," he said. Parents want to have the values their children learn in church carried into the classroom, he said.

Our Lady of Hope parish was founded in 2000 with about 300 families who began a capital campaign to raise $15 million for a church-school complex. The church, built like the school in contemporary Gothic architectural style, set to open in October at the corner of Cascades and Algonkian parkways. The church will feature stained-glass windows that are more than 100 years old and were saved from a shuttered church in New York.

The parish, which now has about 1,300 families, has been holding Sunday services at Potomac Falls High School and weekday services at Community Lutheran Church in Potomac Falls.

Saunders said a growing proportion of new parishioners are Hispanic, reflecting overall growth in the diocese. The diocese receives about 12,000 new Catholics each year, and some parishes receive more than 30 new families a month. Many immigrants are attracted to Loudoun because of its large number of government and technology jobs, said Timothy J. McNiff, superintendent of schools for the Diocese of Arlington. "Clearly, like most schools, we have benefited from what's been happening demographically and economically in the area," he said.

Exterior views, this month, show the near-complete Our Lady of Hope Catholic School in Potomac Falls. The school is part of a church-school complex that falls under the authority of the Arlington Diocese. The church's opening is expected in October.

The Rev. William P. Saunders visits the main office at Our Lady of Hope Catholic School in Potomac Falls. The school opens Aug. 29.