Objective This study was designed to 1) identify the most important home/family, peer, school, and neighborhood environmental characteristics associated with weight status and 2) determine the overall contribution of these contexts to explaining weight status among an ethnically/racially diverse sample of adolescents. Design and Methods Surveys and anthropometric measures were completed in 2009-2010 by 2,793 adolescents (53.2% girls, mean age = 14.4 ± 2.0, 81.1% non-white) in Minneapolis/St. Paul, Minnesota schools. Data representing characteristics of adolescents' environments were collected from parents/caregivers, friends, school personnel, and Geographic Information System sources. Multiple regression models controlled for adolescent age, ethnicity/race, and socioeconomic status. Results The variance in body mass index (BMI) z-scores explained by 51 multicontextual characteristics was 24% for boys and 22% for girls. Across models, several characteristics of home/family (e.g., infrequent family meals) and peer environments (e.g., higher proportion of male friends who were overweight) were consistently associated with higher BMI z-scores among both boys and girls. Among girls, additional peer (e.g., lower physical activity among female friends) and neighborhood (e.g., perceived lack of safety) characteristics were consistently associated with higher BMI z-scores. Conclusions Results underscore the importance of addressing the home/family and peer environments in future research and intervention efforts designed to reduce adolescent obesity.