Prenatal exposure to organophosphorus pesticides (OPs) has been associated with a wide range of adverse childhood outcomes –. However, most of these studies rely on OP biomarkers in the general population. These biomarkers disproportionately reflect non-toxic dietary ingestion of metabolites and cannot distinguish between parent pesticides. Exposure metrics that use agricultural pesticide applications may overcome these limitations, but such studies are limited to California. We propose to prepare Arizona’s Pesticide Use Registry as a resource for future studies of exposure to pesticides and childhood health outcomes, and to enhance exposure assessment by incorporating birth certificate-reported farmworker occupation into analyses. Farmworkers are at higher risk of pesticide-associated health risks due to occupational exposures, but farmworkers are difficult to identify and are highly transitory. Thus, we also propose a pilot study of prenatal exposure to OPs and preterm birth among farmworkers to assess the feasibility of this approach for future studies.