Rifting between Newfoundland and Iberia occurred in two distinct phases--the first late Triassic to early Jurassic, the second late Jurassic to early Cretaceous--culminating in the creation of the North Atlantic Ocean. A dynamic modelling method was used to examine the implications of multiple phases of rifting on the development of the Newfoundland-Iberia conjugate margins. The models predicted a lack of magmatism on these margins, and suggested that extension was significantly greater in the second rifting phase than in the first; these predictions agree with geological observations. The models could not predict the existence of highly thinned continental crust on both conjugate margins, however. In addition, a set of generic models roughly based on the Newfoundland and Iberia margins suggested that, where two rift phases occur, the site of the original rift usually will not be favored for extension when stretching resumes.