Asphaltene precipitation is traditionally modeled using the Flory-Huggins polymer solution theory. The existing thermodynamic models, generally, do not take into account the aggregation/association phenomena in the system. This work aims at providing a monodisperse thermodynamic model for estimating asphaltene precipitation by taking into account the aforementioned phenomena. The chemical theory of associated solutions with physical interactions along with the Flory-Huggins polymer solution theory is applied to develop this model. The results of this method are compared with some selected experimental data from the literature. It is shown that taking into account the aggregation/association phenomena in the system can lead to better predictions of the model. Moreover, it is shown that this method simplifies to the existing activity coefficient based models when ignoring the association.