Direct observations of the surface crack opening displacement (SCOD) of surface and corner fatigue cracks were made on samples of Ti-6Al-4V under both cyclic and static loading conditions. The experiments were conducted in situ in a scanning electron microscope. Results show that surface residual stresses can significantly affect crack opening behavior—thus crack growth behavior—even when the crack has grown well beyond the zone of residual stress. An analytical approach was developed and used to predict SCOD for Mode I part-through cracks based on crack geometry and the boundary integral technique. Correlation with independent results for macrocracks and values for microcracks measured in this program are excellent for the case of zero residual stress. The analytical approach is currently being extended to more accurately account for the presence of residual stress gradients.