Resins are interesting catalysts for organic reactions, which are characterized by a remarkable swelling behavior upon exposure to liquids, typically resulting in selective sorption in the case of mixtures. Hence, when constructing kinetic models for reactions catalyzed by such resins, the component partitioning between the bulk liquid and polymer liquid and its effect on their thermodynamic activities have to be properly taken into account. A kinetic model is developed for acidic resin-catalyzed esterification, while comparing two scenarios for capturing the thermodynamics within the resin pores. For the specific case study on a single resin with a specific solvent, compensation effects between the calculated thermodynamic activities in the resin and the estimated rate coefficients render only minor performance differences between the two scenarios. Still, aiming at extending the scope toward other solvents and/or resins, it is deemed crucial to explicitly account for the resin's selective sorption and swelling behavior.