In a study that highlights the fluidity of religious affiliation in America today, Hindus stand out as the group with the most stable religious identity, while Buddhists struggle hardest to pass the faith from one generation to the next. Ninety percent of Hindus marry within their own faith, and eight-in-ten Hindus who were raised Hindu remain so as adults, according to the U.S. Religious Landscape Survey, released Monday (Feb. 25) by the Pew Forum on Religion & Public Life. In contrast, only 45 percent of Buddhists are married to another Buddhist, and only half of Buddhists who were raised in the faith remain Buddhists as adults. The survey, based on interviews with 35,000 U.S. adults, helps put a face on two faiths imported from Asia that have long been hard to quantify. Numbers for both groups "should be viewed as minimum estimates," researchers wrote, because non-English-speaking immigrants may have been excluded. The survey estimated there are 1.6 million American Buddhists (0.7 percent of the adult population). A majority (53 percent) are white, while one-third are Asian. Hindus, meanwhile, number about 900,000, or 0.4 percent of all adult Americans. The fact that eight in 10 Hindus are foreign-born may help explain the high retention rates, said Vasudha Narayanan, a Hindu scholar at the University of Florida. "Many (Hindu Americans) are from India, so they still feel ethnically different and have remained Hindu" and sought to marry fellow Hindus, she said. But Narayanan said that stability won't last forever. "Already we are seeing members of the next generation, who are assimilated, marrying into other traditions," she said. The study also revealed Hindu Americans have higher-than-average income and education levels as compared to other Americans. In addition, six in 10 Hindu are male, a pattern that reflects immigration trends, said Narayanan. The Pew Forum data also do not capture the cultural influence of Hinduism in America, said Narayanan. "Many Americans practice religious yoga or mediate or believe in reincarnation or karma without explicitly calling themselves `Hindu."' For Buddhists, the data show "convert Buddhist communities face a significant challenge in engaging their children and keeping them in the tradition," said Thomas Tweed, a professor of religious studies at the University of North Carolina at Chapel Hill. Many Buddhist converts "didn't really attempt to bring their children into Buddhism," added Robert Seager, a religious studies professor at Hamilton College in Clinton, N.Y. "They said, `I don't want to lay my trip on my kids."' Immigrant Buddhists, who may have "stronger institutional commitments" than converts, were probably under-represented in the survey data, Seager said. He theorized, however, that retention may also be low among children born to waves of Vietnamese and Cambodian refugees who came to the United States a generation ago. "With the Boomer population (of Buddhists) aging," Seager said, "I do worry about Buddhism in America evaporating with time."