The CIR Expert Panel assessed the safety of dicarboxylic acids and their salts and esters as used in cosmetics. Most dicarboxylic acids function in cosmetics as pH adjusters or fragrance ingredients, but the functions of most of the salts in cosmetics are not reported. Some of the esters function as skin conditioning or fragrance ingredients, plasticizers, solvents, or emollients. The Expert Panel noted gaps in the available safety data for some of the dicarboxylic acid and their salts and esters in this safety assessment. The available data on many of the ingredients are sufficient, however, and similar structural activity relationships, biologic functions, and cosmetic product usage suggest that the available data may be extrapolated to support the safety of the entire group. The Panel concluded that the ingredients named in this report are safe in the present practices of use and concentration.