Over the years, aviation has seen a steady improvement in aircraft performance and efficiency with implementation of lighter and stronger aerospace alloys. Yet, there are additional cuts in weight and manufacturing costs to be had by combining new alloys with advanced design concepts. Integral or monolithic structure is a popular concept that has been proposed to achieve the design targets set for next generation aircraft. But, there is still much to learn before monolithic design concepts can be implemented commercially, and the current program was an initial step to further the development. This program evaluated the fatigue crack propagation characteristics of sub-sized integrally stiffened panels (ISP) representative of lower wing structure. Both extruded ISP’s and those “hogged-out” of plate were evaluated with new Alcoa alloys in combination with two concepts for improved damage tolerance. In one concept, selective reinforcement, adhesively bonded straps, were added to the ISP. The adhesively bonded straps bridge cracks and carry additional load much like a conventionally fastened stiffener would as a crack propagates underneath in the wing skin. Thus, selective reinforcement improves the damage tolerance and adds fail-safety to the ISP design. For the second concept, extruded ISP’s were processed to obtain a specific crystallographic texture for improved fatigue propagation resistance. The results from this program illustrate the great potential for advanced metallic aerospace design concepts, and they provide a foundation for future programs to evaluate monolithic structure.