The objectives of this research program are to investigate and clarify fundamental questions on compressibility behavior of natural soils and to develop or refine methods for measurement of compressibility parameters, interpretation of field observations, and analysis of settlement of structures. The specific questions to be investigated include the uniqueness of the end-of-primary void ratio-effective stress relationship, behavior of the coeffi- cient of lateral pressure, methodology for settlement and pore pressure analyses, and secondary compression of clean sands. The research method relies on exacting experimental techniques and long-term laboratory and field observations as well as mathemati- cal modeling and numerical analysis. A distinct feature of the project is that high quality undisturbed samples of natural clays are being used in laboratory investigations. The intention is to rely on observation as the primary basis for developing physical and mathematical models and to assure the generality of the concepts through the use of an extensive data base and comparisons with soil response to full-scale construction. Previous accomplishments confirm that a clear understanding of consolidation is: a significant event in the geological history of natural soil deposits; an important mechanism in soil improvement through densification; and an intended stage or an undesirable effect in laboratory or in situ measurement of soil properties. Settlements associated with consolidation and corresponding changes in permeability, deformability and shear strength of soils are all important factors of practical concern in geotechnical design, construction and performance of structures.