Study objective: To investigate the relation between neighbourhood socioeconomic and ethnic characteristics with depressive symptoms in a population based sample. Design: Cross sectional data from the CARDIA study, including the Center for Epidemiological Studies depression scale score (CES-D). Neighbourhoods were 1990 US census blocks of 1000 people; six census variables reflecting wealth/income, education, and occupation investigated separately and as a summary score; neighbourhood racial composition (percentage white and black) and individual level income and education were also examined. Setting: Participants recruited in 1985/86 from community lists in Birmingham, AL; Chicago, IL; Minneapolis MN; from a health plan in Oakland, CA. Participants: 3437 adults aged 28-40 years in 1995/96: 24% white men, 27% white women, 20% black men, 29% black women. Main results: For each race-sex group, CES-D was inversely related to neighbourhood score and individual income and education. Associations of neighbourhood score with CES-D became weak and inconsistent after adjusting for individual level factors; personal income remained strongly and inversely associated with CES-D. Age adjusted mean differences (standard errors) in CES-D between the lowest and highest income categories were 3.41 (0.62) for white men, 4.57 (0.64) for white women, 5.80 (0.87) for black men, and 5.74 (0.83) for black women. For both black and white participants, CES-D was associated negatively with percentage of white people and positively with percentage of black people in their census block, before, but not after, adjustment for individual and neighbourhood socioeconomic variables. Conclusions: Neither neighbourhood socioeconomic characteristics nor ethnic density were consistently related to depressive symptoms once individual socioeconomic characteristics were taken into account.