Objective: This study examines the role of neighborhood context in the accumulation of biological risk factors and racial/ethnic and socioeconomic disparities. Methods: Data came from face-to-face interviews and blood sample collection on a probability sample of adults (n = 549) in the 2002 Chicago Community Adult Health Study. Following the approach of prior studies, we constructed an index of cumulative biological risk (CBR) by counting how many of eight biomarkers exceeded clinically defined criteria for “high risk”: systolic and diastolic blood pressure, resting heart rate, hemoglobin A1c, C-reactive protein, waist size, and total and high-density lipoprotein cholesterol. Data are presented as incidence rate ratios (IRRs) based on generalized linear models with a Poisson link function and population-average estimates with robust standard errors. Results: Non-Hispanic blacks (n = 200), Hispanics (n = 149), and people with low (n = 134) and moderate (n = 275) level of education had significantly higher numbers of biological risks than their respective reference groups (IRR = 1.48, 1.59, 1.62, and 1.48, respectively, with p <.01). Black-white (p <.001) and Hispanic-white (p <.003) disparities in CBR remained significant after adjusting for individual-level socioeconomic position and behavioral factors, whereas individual-level controls substantially diminished the low/high (p <.069) and moderate/high (p <.042) educational differences. Estimating "within-neighborhood" disparities to adjust for neighborhood context fully explained the black-white gap in CBR (p <.542) and reduced the Hispanic-white gap to borderline significance (p <.053). Neighborhood affluence predicted lower levels of CBR (IRR = 0.82, p <.027), but neighborhood disadvantage was not significantly associated with CBR (IRR = 1.00, p <.948). Conclusions: Neighborhood environments seem to play a pivotal role in the accumulation of biological risk and disparities therein. © 2011 by the American Psychosomatic Society.