A contested racial identity refers to incongruence between personal racial identification and external racial categorization. For example, an individual may self-identify as White, but be perceived by most others as non-White. Documenting racial contestation is important because racialized experiences are shaped not only by the racial classification that individuals claim for themselves but also the external racial attributions placed on them by others. Focusing solely on monoracial identifying adults, this study answers three key questions about racial contestation: (a) How common is it? (b) Who is most likely to report experiencing it? and (c) How is it related to aspects of racial identity such as racial awareness, racial group closeness, and racial identity salience? Employing the 2006 Portraits of American Life Study, results suggest that reports of racial contestation among monoracial identifying adults are more common than some studies suggest (6% to 14%)—particularly among the fastest growing racial groups in the United States, including Latina/os and Asians—and that experiences of racial contestation are often associated with immigrant generation, ancestry, and phenotypical characteristics. Ordinal logistic regression analyses indicate that individuals who report experiencing racial contestation are no more aware of race in everyday life than other U.S. adults, but they feel less close to other members of the self-identified racial group and report lower levels of racial identity salience than their noncontested counterparts. These results point to a thinning of racial identity among the racially contested.