The stress-strain response of Cold Lake oil sands at confining stresses and temperatures up to 18 MPa and 200°C, respectively, was studied in a triaxial apparatus using 89-mm full diameter cores. Tests that have been performed include conventional triaxial tests such as hydrostatic compression, initial Young's modulus determination, and cyclic drained and undrained compression. Tests involving pore-pressure increase and decrease under constant total stresses were also performed t o simulate the stress path encountered in the field during the cyclic steam stimulation process. Treating oil sand as a particulate medium, possible modes of granular interaction were explored for all tests along different stress paths. Four modes of granular interaction were identified: ( i ) contact elastic deformation, ( i i ) rolling, (iii) shear dilation, and ( i v ) crushing. These modes provide a useful framework for explaining the behaviour arising from the effects of variation in void ratio owing to sample disturbance, stress level, stress path, induced anisotropy, and temperature. Other behaviour relating to critical state, localized shear deformation, and load-unload-reload are also examined.