["Journal for the Scientific Study of Religion, EarlyView. ", "\nABSTRACT\nThis article reports key findings of a split‐sample experiment comparing conventional measures of single‐choice religion and new measures of multi‐religiosity. Although conventional measures implicitly assume congruence among religious affiliation, belief, and practice within a single religion, the new measures are designed to capture multi‐religiosity by accounting for belonging to, belief in, or practice of more than one religion. The findings show that although only about 6% of Americans affiliate with or routinely practice two or more religions, about 60% said they somewhat or very much believed in two or more religions. After combining Protestantism and Catholicism into a single Christian religion and restricting it to those who believe very much, 16.3% of respondents still report believing in two or more religions. Asian Americans are more likely to be multireligious than non‐Asian Americans but less than people in East Asian societies. These findings call for further analyses and additional surveys to better understand the patterns revealed by the new measures.\n"]