The perception of transparent objects from images is known to be a very hard problem in vision. Given a single image, it is difficult to even detect the presence of transparent objects in the scene. In this paper, we explore what can be said about transparent objects by a moving observer. We show how features that are imaged through a transparent object behave differently from those that are rigidly attached to the scene. We present a novel model-based approach to recover the shapes and the poses of transparent objects from known motion. The objects can be complex in that they may be composed of multiple layers with different refractive indices. We have conducted numerous simulations to verify the practical feasibility of our algorithm. We have applied it to real scenes that include transparent objects and recovered the shapes of the objects with high accuracy.