Proterozoic to Tertiary sedimentary strata in the Canadian Beaufort Sea-Mackenzie Delta region were deformed into a regional fold and thrust belt during Tertiary orogenesis. Seismically-imaged fold structures are commonly asymmetric and many are clearly detached. Decollement horizons occur at several stratigraphic levels. The Tertiary Beaufort Foldbelt developed as an arcuate array of contractional structures and associated (coeval) longitudinal normal faults and oblique-slip fault zones. The extensional and transcurrent faults accommodated variations in the direction and magnitude of Tertiary shortening. Tertiary deformation shows a general foreland-younging trend, away from the craton. The most intense pulses of Tertiary deformation occurred in the Early to Middle Eocene and Late Miocene. The Late Miocene pulse of tectonism affected some parts of the region more than others, thus segmenting the region into variably deformed areas. The Tertiary structural evolution of the Beaufort Sea-Mackenzie Delta region reflects a complex interplay between crustal shortening, syntectonic sedimentation and an array of boundary conditions imposed by basin margins and pre-existing basement structures. Basement controls on Tertiary deformation appear likely in some parts of the region.