A model for handling the effect of water on nylon equilibria and kinetics has been developed and tested. Observed variations in the equilibria and kinetics are attributed to microscopic phenomena, not an empirical expression. The equilibrium variation is modeled based on two states of water in the nylon melt, and the kinetic variation is modeled as due to a changing dielectric constant. All reactions are assumed to be acid catalyzed. Results are good at water to polymer ratios ranging from 0.01 to 30 and from temperatures from 200 to 280 degrees C. The model framework also allowed the calculation of interchange rates and ring oligomer concentrations. The model is compared with published data and ether proposed models.