ABSTRACT Since its inception in 1999, the CHAMACOS study is one of the longest running cohort studies examining the impact of early life environmental exposures on neurodevelopment, growth, and respiratory disease and the only one focused on low-income, Latino children in a farmworker population. We have collected extensive health, exposure, demographic, neighborhood, and regional data, as well as biological (e.g. blood, urine, breastmilk, hair, saliva, deciduous teeth) and environmental (e.g. dust, allergens) samples at multiple visits and have created a large biorepository with more than 300,000 samples stored for future use. We have used banked specimens and archived data to demonstrate relationships of pre- and postnatal exposures to pesticides, flame retardants, and other chemicals with poorer neurodevelopment, reduced lung function, obesity, and other outcomes. We have shown that environmental exposures affect a multitude of molecular mechanisms that influence health, such as PON1 enzymatic activity, adipokine and isoprostane levels, DNA methylation and miRNA expression. The CHAMACOS resources have supported multiple NIH, EPA, and non- federal grants and trainees, including collaborations with other institutions. With well over 150 publications, CHAMACOS is a successful and well-established environmental epidemiology cohort. The main goals of the parent grant (R24ES028529) were to maintain and improve the infrastructure required for management of this vast trove of data, the laboratory facilities to ensure the safety of hundreds of thousands of samples, and the effort to keep families engaged and participating in this long-running study. However, the School of Public Health (SPH) Biorepository and Children’s Environmental Health Laboratory, which house the biological and environmental specimens has experienced an unexpected shortfall of funding this year. The purpose of this administrative supplement is to provide additional critical funding to the SPH Biorepository. Supplement funds will be used to secure the position of early stage investigator, Dr. Karen Huen, who has been working with the CHAMACOS study for many years. Dr. Huen’s extensive skills and experience at the Children’s Environmental Health Laboratory and SPH Biorepository are crucial for the longevity of the Biorepository and the research that it supports. As an environmental and molecular epidemiologist, Dr. Huen has published extensively on the functional genomics of PON1 and on relationships of environmental exposures with epigenetic profiles in CHAMACOS children. For this supplement, she will support the main goals of the parent grant to maintain the vital functions of the SPH Biorepository. She will continue to train students, researchers, and new faculty members on essential skills for utilizing the invaluable specimens stored at the Biorepository from development and validation of molecular assays to statistical analysis of complex datasets. Further, securing her posi...