The early care and education (ECE) environments of children offer a potentially critical setting for curbing the epidemic levels and marked disparities in obesity in the U.S. by race/ethnicity, nativity and socioeconomic status. Subsidized care funded through the Child Care and Development Fund (CCDF) provides one such mechanism for targeting minority and low income children and, along with Head Start (HS), is the federal government's largest investment in ECE. To date, however, the evidence about the role of subsidized care, HS and other ECE environments in child obesity is currently insufficient to guide policy. Lacking a nationally-representative experimental trial, the next best option for developing national insights about the role of HS and subsidized care in curbing child obesity is to employ longitudinal, nationally-representative observational data. We employ two such data sources, the 2006 Head Start Family and Child Experiences Survey (FACES) and the Early Childhood Longitudinal Study Birth Cohort (ECLS-B) to study change in children's body mass index (BMI) z-scores. We evaluate pooled-survey methodologies and quasi-experimental methods to help address problems of sample power and selection of families into care types.