A most significant activity regarding the successful evolution of ICME is the integration of microstructural characterization with modeling and simulation. Traditionally, this has been done by making 2-dimensional sections of samples and imaging these in a microscope that provides sufficient spatial resolution to permit imaging of features of interest. Some researchers have developed rigorous methods based on stereology to transform information from these 2-dimensional projections to 3-dimensional descriptions. More recent studies have been focused on the development of direct 3-dimensional characterization. Two approaches have been employed, one involving serial sectioning of a sample followed by reconstruction to yield 3-dimensional views, and the other tomography. Examples of these techniques will be presented, and their importance in development of computational models will be demonstrated.