Abstract: Hispanic children have a higher prevalence of overweight/obesity than their non-Hispanic counterparts. Perinatal maternal health status and lifestyle behaviors are recognized as important risk factors for childhood obesity. Pre-pregnancy maternal obesity is linked to higher infant birth weight and increased risk of offspring obesity. The maternal diet and metabolic profile during preconception has been shown to adversely affect the subsequent health of the offspring, including the development of obesity. However, the data are scarce for Hispanics from various backgrounds and limited, in general, due to the lack of standardized documentation of preconception health. The Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a cohort of 16,415 adults (including 3,801 women 18-44y) from four U.S. cities, is the largest health study of Hispanics/Latinos in the US. Baseline data, including cardiometabolic markers and diet, were collected from 2008 to 2011, and reproductive history is being collected at visit 2 from October 2014 to 2017. Hence, HCHS/SOL offers a unique opportunity to prospectively investigate the role of preconceptional maternal health status (cardiometabolic biomarkers and diet) on the development of childhood obesity and to understand drivers of overeating, such as food reward-related behaviors and psychological stress of women as predictors of child feeding practices and weight. This ancillary study proposes to recruit 440 mother-child dyads; these are women of reproductive age with a child (ages 3-7y) born since the baseline examination to assess child's weight, height and adiposity (total fat mass as measured by DEXA), eating and other lifestyle behaviors, and women's food reward-related behaviors. We propose to identify early modifiable determinants of child's weight and adiposity status that are not attributable to the genetic environment. This is a novel use of an existing cohort to answer very timely and important research questions that have the ability to contribute to the development of intervention studies during this very critical time period in the lifecycle of both the mother and child for the Hispanic population.