The current study investigated the heterogeneity of borderline personality disorder (BPD) symptoms in a sample of 382 inner-city, predominantly African American male substance users through the use of latent class analysis. A 4-class model was statistically preferred, with 1 class interpreted to be a baseline class, 1 class interpreted to be a high-BPD class, and 2 classes interpreted as intermediate classes. As a secondary goal, we examined the resulting BPD classes with respect to relevant clinical correlates, including temperamental vulnerabilities (affective instability, impulsivity, and interpersonal instability), childhood emotional abuse, drug choice, and co-occurring mood and anxiety disorders. The high-BPD class evidenced the highest levels of the temperamental vulnerabilities and environmental stressors, the baseline class evidenced the lowest levels, and the 2 intermediate classes fell in between. In addition, the high-BPD class had a higher probability of cocaine and alcohol dependence, as well as mood and anxiety disorders, than did the baseline class. Rates of alcohol use and mood disorders for the intermediate classes fell in between the high-BPD and the baseline classes. Results are discussed in relation to the current diagnostic conceptualization of BPD. (Contains 2 figures and 5 tables.)