Provided are compositions comprising an ethylene acid copolymer and a functional ethylene copolymer. The ethylene acid copolymer comprises in-chain polymerized units derived from ethylene and at least one ethylenically unsaturated monocarboxylic acid or derivative thereof. The functional ethylene copolymer comprises in-chain polymerized units derived from ethylene and at least one ethylenically unsaturated dicarboxylic acid or derivative thereof. Optionally, the ethylene acid copolymer or the functional ethylene copolymer further comprises one or more copolymerized alkyl(meth)acrylates. The carboxylic acid functionalities of the ethylene acid copolymer and the functional ethylene copolymer may be at least partially neutralized to form carboxylate anions. Preferred counterions include one or more alkali metal, transition metal, or alkaline earth metal cations. The compositions are useful for fabricating films, sheets and other shaped articles, such as packages.