It has been determined from an infrared analysis of miscible blends of n-butyl methacrylate-co-4-vinylphenol and styrene-co-2-vinyl pyridine copolymers that the fraction of hydrogen-bonded carbonyl groups actually increases with temperature. At first glance, this is counterintuitive, but it is entirely consistent behaviour for a multicomponent hydrogen-bonding system containing competing acceptor groups that have disparate enthalpies of hydrogen bond formation.