Regional tectonic features of the western Canadian Cordillera can be interpreted in terms of Middle Jurassic accretion of a single composite superterrane (Stikinia + Wrangellia + Alexander) to ancestral North America. Closure of the intervening Cache Creek‐Bridge River ocean moved the continental edge to a new position west of the accreted superterrane. The Coast Belt is primarily a succession of superimposed Middle Jurassic to early Tertiary magmatic arcs related to prolonged subduction of Pacific Ocean lithosphere beneath the new North American margin. Discrete magmatic pulses, separated by lulls or periods of relative quiescence, successively overprinted the new margin. The Insular and Intermontane superterranes, previously viewed as widely separate entities prior to mid‐Cretaceous time, were already amalgamated before an initial Middle Jurassic overprint produced an ancestral Coast Belt. Late Jurassic to Early Cretaceous rift‐related(?) marine basins, mid to Late Cretaceous compressional structures, and early Tertiary extensional features coincident with the Coast Belt are subsidiary intraplate attributes that reflect external adjustments in plate motions within a primary, subduction‐related Andean magma