America’s Eastern Orthodox parishes have grown 16 percent in the past decade, in part because of a settled immigrant community, according to new research.

Alexei Krindatch, research consultant for the Standing Conferences of the Canonical Orthodox Bishops in the Americas, said the 16 percent growth in the number of Orthodox parishes is “a fairly high ratio for religious groups in the United States.”

The number of Orthodox parishes has reached 2,370, and the Orthodox community in America consists of more than 1 million adherents across 20 different church bodies, according to the 2010 U.S. Orthodox Census.

The top five largest Orthodox churches in the U.S. are Greek Orthodox (476,900), Orthodox Church in America (84,900), Antiochian Orthodox (74,600), Serbian Orthodox (68,800) and Russian Orthodox (27,700).

Two of these church bodies — the Bulgarian Orthodox Eastern Diocese and the Romanian Orthodox Archdiocese — experienced a growth rate of over 100 percent.  Both churches began with a small number of parishes in 2000 and are supported by a community of established Eastern European immigrants.

“It takes immigrant communities a little while to establish a religious community,” Krindatch said. “They settle, then begin to think about their religious lives.”

Even though the majority of Orthodox church bodies grew, some lost parishes. The Ukrainian Orthodox Church of the USA, Patriarchal Parishes of the Russian Orthodox Church and Armenian Apostolic Church of America all experienced a slight decrease in the number of parishes.

The study, which was part of the national Religious Congregations and Membership Study 2010, also shows that just 27 percent of members attend Orthodox churches regularly.

Krindatch said the definition of each of the groups affected this statistic. Church “adherents” was the most inclusive category, consisting of anyone who occasionally participated in church life, while “regular attendees” are those who attend church on an almost weekly basis.