"It's growing," said Omar Housni, the mosque's Imam, or prayer leader. "It's a combined fact of immigration and some conversion."
One of those converts is Lisa Dahbi, who became a Muslim in December after years of contemplations.
Dahbi, of Greencastle, Pa., said her husband is a Muslim. But she accepted the faith only after years of studying the major religions.
Born a Christian, Dahbi, 22, said she never really believed or understood the religion. But the Koran, Islam's holy book, appealed to her.
"It seemed to make the most sense to me," she said. "It took me a long time to make the decision . I wanted to be sure."
The dramatic growth in Islam in the Tri-State area, though the numbers are still small, mirrors a similar rise of the religion throughout the country. An estimated 6 million Americans are Muslim and experts predict the religion could overtake Judaism as the nation's second-most common religion early next century.
As a result, mosques are going up in small, rural communities like Hagerstown throughout America.
For Muslims like Waheed, whose medical specialty is lung diseases, it could not have come soon enough.
"We had to have something like this here," he said.
The Hagerstown mosque was built by a small coterie of well-educated professionals who have moved to the area from Muslim countries. Many are doctors.
But Housni stressed that the community draws support from other quarters. Several area Muslims work at Citicorp Credit Services and several come from both sides of the bars at the prison complex south of Hagerstown.
"Some of them work in jail. Some of them are in jail," Housni said.
Housni said the growth of Islam in the Tri-State region is apparent during eids, which are special days of celebration.
A celebration of the end of the holy month Ramadan, for example, attracted about 300 people from a four-state area this year, Housni said. The gathering was so large that a community hall in Maugansville had to be rented.
Housni said the eid marking the end of the holy pilgrimage to Mecca will likely draw as many or more.
Area Muslims said they came to Hagerstown for the same reasons other new residents come. Housni graduated from the Islamic University and came to Hagerstown about a year ago when the mosque needed a prayer leader.
"There was a need here. That's why I came here," he said.
Waheed came to the United States to study medicine, figuring he would return to Pakistan.
"But after seeing it here, I liked it," he said.
Waheed said raising his children Muslim in a predominantly Christian society is difficult. Harder is competition from "TV and all the bad influences" that Jewish and Christian parents also worry about, he said.
But Waheed, 48, said the mosque provides a safe haven.
"It has been a lot easier to have a community feeling," he said.
That same community feeling also attracts newcomers like Dahbi. She said it helps cushion the doubts she gets from others when she wears traditional Muslim clothing or does things that set her apart as a minority.
Dahbi noted the increasing numbers of area Muslims with satisfaction.
"I hope for it. I believe it's the truth and I hope as many people as possible can find it," she said.