Methods for making epoxidized fatty acid alkyl esters. Such epoxidized fatty acid alkyl esters can be prepared by epoxidizing a natural oil with an acid and a peroxide. Residual acid in the epoxidized natural oil is not neutralized, such as with a base, prior to esterification to produce the epoxidized fatty acid alkyl esters. Epoxidized fatty acid alkyl esters can be employed in plasticizers, either alone or in combination with other plasticizers, such as epoxidized natural oils. Such plasticizers in turn may be used in the formation of polymeric compositions.