The United States Navy has historically been interested in the development of fracture safe materials for ship construction, and in developing fracture mechanics criteria for design considerations. Recently, a substantial research effort has been directed to the development of J-Integral technology. The purpose of this presentation is to review recent Navy advances in this area. The main points will include a discussion of the applicability of the J-Integral to fracture in ductile materials, the development of test procedures for J_Ic, recent results in the areas of J-controlled crack growth, dynamic J-Integral properties, and instability criteria based on the J_I versus crack growth resistance curve.