Objective To compare infant race/ethnicity based on birth certificates with parent report of infant race/ethnicity in a survey. Data Sources The 2007 Oklahoma birth certificates and SEED for Oklahoma Kids baseline survey. Study Design Using sensitivity scores and positive predictive values, we examined consistency of infant race/ethnicity across two data sources (N = 2,663). Data Collection/Extraction Methods We compared conventional measures of infant race/ethnicity from birth certificate and survey data. We also tested alternative measures that allow biracial classification, determined from parental information on the infant's birth certificate or parental survey report. Principal Findings Sensitivity of conventional measures is highest for whites and African Americans and lowest for Hispanics; positive predictive value is highest for Hispanics and African Americans and lowest for American Indians. Alternative measures improve values among whites but yield mostly low values among minority and biracial groups. Conclusions Health disparities research should consider the source and validity of infant race/ethnicity data when creating sampling frames or designing studies that target infants by race/ethnicity. The common practice of assigning the maternal race/ethnicity as infant race/ethnicity should continue to be challenged.