Mental health campaigns often promote biogenetic beliefs to reduce stigma, but their effectiveness may vary across disorders. Our study (N = 127) examined two components of essentialist beliefs—entitative (i.e., characterizing groupness) and natural kinds (i.e., biogenetic)—about two stigmatized mental disorders (schizophrenia, alcoholism) as well as a somatic disorder (Parkinson's disease), and their relation to prejudice. The three disorders significantly differed in natural kind beliefs (Parkinson's highest, then schizophrenia, and alcoholism lowest) and prejudice (alcoholism highest, then schizophrenia, and Parkinson's lowest), but not entitative beliefs. Entitative beliefs, however, was a stronger predictor of prejudice against schizophrenia than natural kind beliefs even after controlling for social dominance orientation and prior contact. Implications for anti-stigma efforts and strategies are discussed.