During the early stages of continental collision when continental lithosphere is subducted after a prolonged period of normal oceanic subduction, changes in the temperature distribution and stress field of the subducting lithosphere can lead to failure within the lithosphere, and result in detachment of the deeper portion of subducted lithosphere (slab detachment or slab breakoff). We use a 2D time-dependent numerical model to identify the parameters controlling slab detachment and to estimate breakoff depths and time lengths. Temperature and rheology of subducting continental lithosphere are found to control slab detachment.¿ 1997 American Geophysical Union