Although the 14th Amendment of the American Constitution grants citizenship to any person born or naturalized in the country, psychological research suggests that subjective perceptions of who is authentically American is driven by implicit assumptions about who seems typical. People implicitly consider Whites to be more authentically American than racial minorities. This chapter explores how implicit stereotypes about who is American influenced public opinion about Barack Obama during the 2008 presidential election. Data show that these implicit stereotypes evoke doubts about the patriotism of ethnic minorities which in turn promote job discrimination and rejection of public policies proposed by ethnic minorities especially when national security is salient. This chapter also identifies factors that expand vs. restrict people's definition of who is American. Exposure to ethnic minorities engaged in national service expands the inclusiveness American identity whereas exposure to ethnic minorities who embrace their ethnic heritage restricts the definition of American.