Volume I is a summary report which chronicles the research highlights of the entire study of microdamage healing in asphalt concrete. The primary objectives of the study were to: (1) Demonstrate that microdamage healing occurs and that it can be measured in the laboratory and in the field, (2) Confirm that the same fracture properties that control propagation of visible cracks control the propagation of microcracks, (3) Identify the asphalt constituents which influence microdamage and microdamage healing, (4) Establish appropriate correlations between microdamage and microdamage healing in the laboratory and in the field, and (5) Predict the effect of microdamage healing on pavement performance and develop the appropriate constitutive damage models that account for the effects of microdamage healing on the performance of asphalt concrete pavement layers. Volume I describes the success of the project in obtaining each research objective.