This project plans to conduct fundamental studies of the sintering behavior of two model two-phase ceramic systems. One system is the alumina containing sub-micron SiC particles. It is used to test the particle pinning theories of grain growth inhibition. Another system is the slumina containing calcium aluminosilicate glass. It is designed to investigate the effect of pore size distribution on the kinetics of densification during liquid phase sintering. %%%%% This proposal uses two model systems of two-phase ceramic materials, and investigate their sintering behaviors. Detailed experimental characterizations of the material system during the sintering are used to be compared with know theories. Through this approach, better understanding of the sintering of two-phase ceramic systems can be achieved.