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 220,000 samples stored for future use. With over 140 publications, CHAMACOS is a successful and well-established environmental epidemiology cohort. 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. However, 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 have increased over time, while funding for these activities has decreased. The aims for this proposal are to (1) retain participation in the cohort through community engagement, (2) maintain and strengthen data management infrastructure, (3) maintain and enhance the existing biorepository through replacement, repair, and maintenance of aging deep freezers to ensure the integrity of samples and improvements to systems to track samples used for multiple research grants, pilot studies, and collaborations, (4) conduct validation, pilot, and feasibility studies to investigate new methods of assessing environmental exposures, develop best practices for biorepositories, and explore novel methodologies related to metabolomics, genomics, and the microbiome, and (5) develop a data sharing portal to encourage use by outside collaborators of existing CHAMACOS data. In summary, infrastructure support for the CHAMACOS cohort study will preserve specimens, ensure well- documented data for future studies and data sharing, and maintain participant retention, assuring effective future use of these valuable resources. This maintenance grant will thereby strengthen our ability to answer key questions about the impact of environmental exposures on health over the life course and will assure that the extensive resources generated by the CHAMACOS study will be effectively used by investigators worldwide for years to come.