The avian eggshell is one of the most rapidly mineralizing biological systems known. By understandi'ng the key components and steps in this process, we hope to provide relevant information for fabrication of ceramic composites. The calcification of the eggshell occurs in three main steps: 1) fabrication of an organic matrix, 2) nucleation of an inorganic phase on the organic matrix, and 3) space-filling growth of the calcite phase. The different layers of an eggshell can be separately isolated and studied. Three approaches have been used in our study of the eggshell: 1) characterization of the organization and chemical composition of the shell, 2) selective removal or blocking of particular components to improve the remineralization of demineralized shells, and 3) addition of new components to produce composite ceramics of different kinds. In this preliminary communication, the organization of the shell matrix and membranes and their association with the crystal phase, the immunohistochemical occurrence and distribution of types I and X collagen, and of different proteoglycans are reviewed. Also the preliminary findings of the remineralization of the intact or modified eggshell are presented. These experiments allow us to identify the essential steps in forming a natural composite ceramic.