The Report provides comprehensive toughness criteria for welded ship hulls that can be used for steels of all strength levels. Because of the fact that stress concentrations are always present in large complex welded structures and therefore high stresses as well as discontinuities or flaws will be present in welded ship hulls, primary emphasis in the proposed fracture-control guidelines is placed on the use of steels with moderate levels of notch-toughness and on the use of properly designed crack arresters. In general, concepts of fracture mechanics are used to develop the material toughness level that is required for fail-safe operation of welded ship hulls.