Despite the detrimental effects of moisture damage in asphalt pavements, few macroscale models are capable of modeling this important phenomenon. Existing models have limitations in accounting for the irreversibility and time dependency of moisture-induced damage. This study presents a moisture damage model based on continuum damage mechanics. Adhesive and cohesive moisture damage phenomena are modeled independently; this procedure allows for the introduction of fundamental mechanical properties for each process and for modeling the transition between adhesive and cohesive damage. Two- and three-dimensional simulations are performed, and the results of the simulations are presented to demonstrate the applicability and utility of these micromechanical computational models. It is shown that the proposed moisture damage model can simulate the effect of moisture damage on the mechanical response of asphalt concrete subjected to different loading conditions. The model also provides useful insight into the effect of mixture design and material properties on resistance to moisture damage.