Small-scale analogue models were used to investigate the process of Cretaceous orthogonal extension in the West Antarctic Rift System. The models considered the transition from the East Antarctic Craton to a weaker lithosphere, and the results support previous hypotheses about the strong control exerted by lateral variations in lithospheric structures on the process of extension. Strain was mostly accommodated at the boundary between the two types of lithosphere, with a relative uplift of the cratonic block which remained essentially undeformed. Conversely, the weaker lithosphere showed wide-rifting style geometry, locally associated with core complex-like structures. In agreement with the natural prototype, this tectonic scenario led to a long-lasting extension without continental break-up, and to the absence of relevant surface magmatism. © 2007 Blackwell Publishing Ltd.