Novel ester compositions are prepared by reacting 1) at least one diol, glycol or oligomeric glycol with 2) a mixture of at least one aromatic monocarboxylic acid and at least one aliphatic monocarboxylic acid containing from 2 to 4 carbon atoms. The compositions are effective plasticizers for a variety of polymers, particularly those employed in water-borne adhesives. The freezing point of the present ester mixtures and their efficacy as plasticizers and other types of additives and/or modifiers for a variety of polymer compositions can be varied by adjusting the relative concentrations of the aromatic and aliphatic acids used to prepare the ester composition.