Psychosocial self‐report measures are increasingly used in primary health care settings. This experiment examined the impact of response bias on self‐report of psychosocial information in 74 Blacks and 52 Whites. Participants completed the Center for Epidemiological Studies‐Depression (CES‐D), Cook‐Medley Hostility/Stress (CM), Buss‐Durkee Hostility (BD), and Marlowe‐Crowne Social Desirability (MCSDS) scales. Blacks reported greater negative affect than Whites on 2 of 15 scores, and their MCSDS scores were 30% higher. After using MCSDS scores as a covariate, Blacks showed significantly greater negative affect on 10 of 15 scores. Socioeconomic status did not explain the results. Response bias may affect self‐report of negative affect more in Blacks than Whites. Self‐report instruments may underestimate mood symptoms experienced by Blacks