This study examines whether the increasing ethnic diversity of the United States is changing how the normative content of American identity is defined. It relies on a wide-ranging set of norms to test the claim that an increasingly multicultural America will engender a multicreedal America. In addressing this claim, the study provides an empirical assessment of the “multiple traditions” theory and develops more accurate measures of how Americans view the content of American identity than has typically been included in public opinion research. The results confirm the multiple traditions perspective, showing that a broad range of constitutive norms define being American. A complex and contradictory set of norms exist, and it is difficult to reduce them into a single measure of “Americanism.” The results further show that most Americans, regardless of their ethnic or immigrant background, share this complex view of the norms that constitute American identity, though there are signs of divergence to monitor.