Fetal Alcohol Spectrum Disorders (FASD) describe a highly variable continuum of ethanol-induced developmental defects, including facial dysmorphologies and neurological impairments. With a complex pathology, FASD affects approximately 1 in 100 children born in the United States each year. Due to the highly variable nature of FASD, animal models have proven critical in our current mechanistic understanding of ethanol-induced development defects. An increasing number of laboratories has focused on using zebrafish to examine ethanol-induced developmental defects. Zebrafish produce large numbers of externally fertilized, genetically tractable, translucent embryos. This allows researchers to precisely control timing and dosage of ethanol exposure in multiple genetic contexts and quantify the impact of embryonic ethanol exposure through live imaging techniques. This, combined with the high degree of conservation of both genetics and development with humans, has proven zebrafish to be a powerful model in which to study the mechanistic basis of ethanol teratogenicity. However, ethanol exposure regimens have varied between different zebrafish studies, which has confounded the interpretation of zebrafish data across these studies. Here is a protocol to quantify ethanol concentrations in zebrafish embryos using head space gas chromatography.