Little is known about why minorities have a lower propensity to use private doctors' offices for their usual source of care than non-Hispanic whites. This study used the 2001 Commonwealth Fund's Health Care Quality Survey of adults to determine if this disparity is due to racial and ethnic differences in attitudes about health and healthcare, and perceptions of racial and ethnic discrimination in healthcare. We found that race and ethnic disparities at the site of the usual source of care persisted even after controlling for individuals' attitudes about health and healthcare, and their perceptions about racial and ethnic discrimination in healthcare. We found that the impact of attitudes and perceptions did vary by subgroups. These factors were important for Asians' site of usual source of care but had little impact on African Americans' site of usual of care. However, despite their differential impact by race and ethnicity, attitudes and perceptions were not the source of observed disparities in site of care. Therefore, in addition to focusing on provider-patient relationships, perhaps future research and policymakers should focus on system-level factors to explain and increase minority use of care in private physicians' offices.