The interlayer bond (more specifically the shear stiffness) between two asphalt layers is a critical factor in the long-term performance of asphalt pavements. Extensive tests have been carried out on asphalt pavement specimens and laboratory produced slabs to investigate and describe the interlayer bond under laboratory conditions as realistically as possible. In each case the interlayer bond was investigated using cyclic shear tests. In addition to the test temperature and frequency, the normal stress (representative of the wheel load) and the shear path were varied. Based on the extensive test results, a new model approach was developed to describe the shear stiffness. The test procedure was also modelled and validated based on the test results. Finally, the new model was integrated for the first time into a finite element model to analyse the influence of the interlayer bond on the stress conditions and expected service life in a road pavement.