BackgroundUpon arrival, the prevalence of overweight and obesity is lower in new immigrants than their native counterparts in the U.S. With longer residency in the U.S., these differences converge over time, followed by higher prevalence among immigrants than native U.S. residents. Results from the Live Well project in the Greater Boston area demonstrate the viability of utilizing a culturally adapted, community-based participatory research (CBPR) approach to reduce weight gain among newly immigrated mother–child dyads.MethodsHaitian, Latina, and Brazilian mother–child dyads (n = 390), new to the U.S. (fewer than 10 years) were enrolled in a one- to two-year long CBPR lifestyle intervention that targeted dietary and physical activity behaviors. Attendance was recorded to establish dose. Demographics, anthropometrics, and relevant covariates were collected from participants at baseline, 6, 12, 18, and 24 months. Body Mass Index (BMI) was calculated using objectively measured height and weight. Linear mixed regression models were used to assess change in BMI and BMI z-score of mothers and children respectively.ResultsAt baseline, nearly 75% of mothers and 50% of children were either overweight or obese (BMI ≥ 25.0 and BMI z-score ≥ 85th percentile, respectively). Only 20% of mothers attended all 12 intervention sessions in year 1. Using intent-to-treat analyses, no significant time, intervention, or time × intervention effects were observed for weight change of mothers or children at follow-up. Mothers in the highest quantile (those who attended all 12 intervention sessions) had significant reductions in BMI at 18 months (1.76 units lower, 95%CI: -3.14, -0.37) and 24 months (2.61 units, 95%CI -3.92, -1.29) compared to mothers in the lower quantiles, including those with no exposure. Such dose effects on BMI z-scores were not noted for children.ConclusionsFindings from Live Well demonstrate the viability of utilizing a CBPR approach to address overweight and obesity among immigrant mothers. Given the higher-than-expected prevalence of overweight and obesity among mother–child dyads by ~ 6 years of U.S. residency, and lower maternal participation rates in the intervention, additional research is necessary to identify the optimal intervention length, retention strategies, and approach to jointly support healthy maternal and child weight.