It is shown that a familiar procedure for obtaining stress intensity factors for a plate containing a through crack may be inverted. That is, stress intensity factor measurements may be used to deduce the state of stress that existed in the plate prior to introduction of the crack. This approach to residual stress measurement appears to be superior to existing methods for situations in which the stress gradients in the plane of the plate are large. As an illustration, the residual stress distribution in an electron beam welded aluminum plate is determined.