The undergraduate mental health nursing course is an optimal time to address stigma and prejudice, while developing positive student attitudes toward those who live with mental health conditions. A quasi-experimental, pretest-posttest, nonequivalent-group study with a sample of undergraduate nursing students in New York City (N = 126) was conducted to determine the impact of an undergraduate mental health nursing course on attitudes toward people living with a general mental illness, depression, or schizophrenia. The intervention resulted in a significant reduction in total prejudice scores toward those with a general mental illness when compared to the control (p = 0.033, partial η2 = 0.062). The intervention had no significant impact on total prejudice scores regarding those with depression, or schizophrenia. Subscale analysis revealed the intervention significantly reduced attitudes of fear/avoidance regarding general mental illness (p = 0.040, partial η2 = 0.058) and schizophrenia (p < 0.001, partial η2 = 0.164). There was no impact on authoritarian or malevolent attitudes. Though some attitudes were not amenable to change, this study provides evidence that positive attitudes can be cultivated through undergraduate nursing education. Curricular reform is needed to reduce all facets of prejudice and best prepare future nurses to care for those with mental health conditions.