Naomi Schaefer Riley reports that fewer Mormons (12%) are in interfaith marriages compared to other religions.
Naomi Schaefer Riley, 'Til Faith Do Us Part: The Rise of Interfaith Marriage and the Future of American Religion, Family, and Society (New York: Oxford University Press, 2013), 6
About 20 percent of couples married before the 1960s were interfaith matches. Of couples married in the past decade, 45 percent were. The 2001 American Religious Identification Survey reported that 27 percent of Jews, 23 percent of Catholics, 39 percent of Buddhists, 18 percent of Baptists, 21 percent of Muslims, and 12 percent of Mormons were married to a spouse with a different religious identification.