A new microemulsion adjuvant containing fatty acid esters, an alkylpolyglucoside ester, and ethoxylated fatty alcohols was developed. Physicochemical properties were optimized to improve stability, compatibility, and synergism. The adjuvant was designed to quickly wet and spread on foliage. Biological efficacy trials showed the adjuvant provided equal or better weed control than a reference when mixed with various herbicides applied at suboptimal doses.