We describe a general kinematic method for automatically determining the three-dimensional (3-D) geometry of normal faults at depth from the 3-D geometry of deformed hanging wall horizons. The method should be applicable to normal faults which do not change shape as deformation proceeds. It is a generalization of two-dimensional models and assumes that the hanging wall deforms by arbitrarily inclined bulk simple shear. Deformation in three dimensions is parameterized by the three Euler angles which describe the horizontal slip vector, the rake angle, and the inclination of shear planes. As in two dimensions, differential compaction can be included by assuming that the axis of shortening is parallel to the direction of shear. Three-dimensional fault geometry and the three Euler angles can be automatically determined provided the geometries of two or more hanging wall horizons are known. Here, the method is tested on both synthetic data and on 3-D sand-box models. Synthetic modeling shows that unique solutions can be found and more importantly that the horizontal slip vector can be constrained. Solutions obtained from sand-box models are also encouraging in most cases the method can predict automatically the correct direction of extension and a 3-D fault geometry close to the fault geometry used. Hence arbitrarily inclined bulk simple shear appears to be a good approximation of hanging wall deformation in three dimensions. This general method will allow 3-D palinspastic analysis to be undertaken on 3-D seismic reflection data sets. ¿ American Geophysical Union 1993