This study explored the effects of perceived racism and social support (quantity and quality) on blood pressure reactivity. In a college sample of 64 Blacks (M age = 22.69 years, SD = 6.60), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were assessed before and during a standardized serial subtraction task. Perceptions of racism and the quantity and quality of social support were measured by self- report. Separate multiple regression analyses revealed that perceived racism and social support (neither quantity nor quality) were not independent predictors of SBP or DBP changes (ps > .05). These analyses did indicate that perceived racism interacted with the quantity of social support (p < .002, partial R2 = .175) and with the quality of social support (p < .0007, partial R2 = .195) to predict DBP changes. Perceived racism also interacted with the quantity of social support to predict changes in SBP (p < .02, partial R2 = .11). In general, whereas high social support was related to less marked blood pressure changes under conditions of low perceived racism, high social support was associated with exaggerated blood pressure changes under conditions of high perceived racism. These significant interaction effects persisted after statistically controlling for potential confounders. The findings highlight the importance of examining the joint contribution of real- world experiences and coping resources to blood pressure reactivity in Blacks.