Geodetic measurements in actively deforming areas of the continents reveal the pattern of deformation in the lithosphere. If the dominant forces acting on crustal blocks are tractions al their bases, then the long-term motion of each block will be given by the average velocity of the underlying lithosphere. Slip rates between blocks estimated in this way from recent geodetic measurements across fault zones in the South Island of New Zealand and Southern California are in good agreement with slip rates estimated geologically.