Background: Perinatal morbidity rates are relatively high in the Netherlands, and significant inequalities in perinatal morbidity and mortality can be found across neighborhoods. In socioeconomically deprived areas, 'Western' women are particularly at risk for adverse birth outcomes. Almost all studies to date have explained the disparities in terms of individual determinants of birth outcomes. This study examines the influence of neighborhood contextual characteristics on birth weight (adjusted for gestational age) and preterm birth. We focused on the influence of neighborhood social capital - measured as informal socializing and social connections between neighbors - as well as ethnic (minority) density. Methods: Data on birth weight and prematurity were obtained from the Perinatal Registration Netherlands 2000-2008 dataset, containing 97% of all pregnancies. Neighborhood-level measurements were obtained from three different sources, comprising both survey and registration data. We included 3.422 neighborhoods and 1.527.565 pregnancies for the birth weight analysis and 1.549.285 pregnancies for the premature birth analysis. Linear and logistic multilevel regression was performed to assess the associations of individual and neighborhood level variables with birth weight and preterm birth. Results: We found modest but significant neighborhood effects on birth weight and preterm births. The effect of ethnic (minority) density was stronger than that of neighborhood social capital. Moreover, ethnic (minority) density was associated with higher birth weight for infants of non-Western ethnic minority women compared to Western women (15 grams; 95% CI: 12,4/17,5) as well as reduced risk for prematurity (OR 0.97; CI 0,95/0,99). Conclusions: Our results indicate that neighborhood contexts are associated with birth weight and preterm birth in the Netherlands. Moreover, ethnic (minority) density seems to be a protective factor for non-Western ethnic minority women, but not for Western women. This helps explain the ...