The objective of this proposed research is to study the mechanical properties of lightweight, very highly porous ceramics. Specific objectives of this research include analysis of the tensile and compressive strengths and the crack growth mechanism during failure. These results will be used to model this important class of materials and to test and modify theories for the behavior of open cell ceramic structures and sandwich structures with open cell ceramic cores. This research will concentrate on studies of cellular carbon materials, including coated materials that form sandwich structures.