The present invention is directed to an acrylic copolymer composition prepared from a monomer composition. The monomer composition is essentially free of solvents having a boiling point less than 120° C. and essentially free of acid functional monomers. The monomer composition or acrylic copolymer composition comprises: (A) 30 to 70 percent by weight of a monomer having the structure (I): wherein (i) X is NR′ or O, R′ is hydrogen or is a linear or branched alkyl group having 1 to 18 carbon atoms, and R is a linear or branched alkyl group having 1 to 18 carbon atoms, or (ii) X is N or O and R is a linear or branched alkyl group bonded to X to form a 5- to 7-member ring; based on the total weight of monomers in the monomer composition; and (B) 30 to 70 percent by weight of at least one different ethylenically unsaturated monomer. The present invention is also directed to curable film-forming compositions containing these acrylic copolymer compositions, and substrates coated with the curable film-forming compositions.