This paper, describes an investigation into the linearity limits and rheological properties of various unmodified and modified bituminous binders as well as asphalt mixtures incorporating these binders. The binder tests were undertaken using a dynamic shear rheometer (DSR), while the asphalt mixture tests were undertaken with a purpose-built dynamic, uniaxial tension-compression apparatus. Both polymer modified and process modified binders as well as continuously graded and gap-graded asphalt mixtures have been included in the testing programme. The rheological data indicates strain dependent linearity criteria for both binders (10,000 microstrain) and asphalt mixtures (100 microstrain) at high stiffness values as well as a high temperature strain dependent linearity criterion (1,000,000 microstrain) for elastomeric modified binders. The rheological characteristics of the asphalt mixtures were similar with differences in complex modulus and phase angle only being found at intermediate temperatures and frequencies and attributed to the unique rheological characteristics of the binders.