A major unsolved problem in fracture mechanics concerns the subcritical growth of cracks under fatigue loading to a critical size at which catastrophic fracture occurs. Such growth is the precursor to most service fractures and often involves non-self-similar flaw growth, nonplanar flaws, and nonuniform stress intensity distributions along flaw borders. These geometric complexities coupled with notch geometries and stress gradients which precede and accompany the flaw growth remove the problem from the realm of mathematical tractability. Beginning a decade ago, the author and his associates have been involved in a continuing effort to develop optical methods for extracting stress intensity factor estimates and, more recently, crack shapes and displacement fields from photoelastic models of such bodies. Methods developed involve a marriage between the field equations of linear elastic fracture mechanics with the optical techniques of frozen stress photoelasticity and moire interferometry. After briefly reviewing the analytical foundations of the methods and describing the techniques, this paper presents results obtained from applying the technique to problems of current technological interest in the aerospace and nuclear fields.