Members of racial/ethnic minority groups are less likely than Caucasians to access mental health services despite recent evidence of more favorable attitudes regarding treatment effectiveness. The present study explored this discrepancy by examining racial differences in beliefs about how the natural course and seriousness of mental illnesses relate to perceived treatment effectiveness. The analysis is based on a nationally representative sample of 583 Caucasian and 82 African American participants in a vignette experiment about people living with mental illness. While African Americans were more likely than Caucasians to believe that mental health professionals could help individuals with schizophrenia and major depression, they were also more likely to believe mental health problems would improve on their own. This belief was unrelated to beliefs about treatment effectiveness. These findings suggest that a belief in treatment effectiveness may not increase service utilization among African Americans who are more likely to believe treatment is unnecessary.