We have previously shown that infrared spectroscopy can be used to "count" the number of contacts in hydrogen-bonded system. We use such information to determine appropriate self- and interassociation equilibrium constant values and at the same time take into account the intramolecular "screening" in polymer blends and solutions. The calculated values reported here for screening, and hence the accessibility of the functional groups in a hyperbranched polyester, are based on the interassociation equilibrium constants obtained from the low molecular weight counterparts of the hyperbranched repeat units and give a measure of the accessibility of functional groups in these highly branched systems.