Epoxidized fatty acid methyl esters (EFAMEs), such as those derived from soybean oil (commonly known as epoxidized soybean oil methyl ester), are a class of chemicals where the carbon-carbon double bonds in the fatty acid chains have been converted into oxirane (epoxide) rings. They are typically produced by the epoxidation of unsaturated fatty acid methyl esters (FAMEs) using peracids or hydrogen peroxide. The primary industrial application of EFAMEs is as a bio-based plasticizer and stabilizer for polyvinyl chloride (PVC) and other polymers. The epoxide groups can act as secondary plasticizers and, more importantly, as scavengers for hydrochloric acid (HCl) released during PVC processing and aging, thereby providing thermal and light stability. Additionally, EFAMEs are investigated as reactive diluents or crosslinking agents in coatings, resins, and composite materials, leveraging the reactivity of the epoxide ring for polymerization or chemical modification. As bio-derived and often non-toxic alternatives to phthalate plasticizers, EFAMEs are gaining attention in the development of more sustainable and environmentally friendly polymer formulations. Their properties, such as plasticizing efficiency and compatibility, depend on the source oil and the degree of epoxidation.