Many dynamic graphics displays appear three-dimensional (3D) because of our ability to reconstruct a rotating 3D configuration from its two-dimensional (2D) projection. This ability to infer 3D shape from 2D motion might be considered to be independent of stereopsis because only one eye's view is necessary. On the contrary, however, our data suggest that the mechanisms for both stereopsis and depth-from-motion are not independent but rather must share some components.