A large strain theory of one-dimensional consolidation for normally consolidated and overconsolidated or aged clays which considers the changes in compressibility and permeability during the consolidation and includes secondary compression, shows that the consolidation process in clays is controlled by indexes of compression, recompression, secondary compression, permeability, and the critical pressure ratio, load-increment ratio, and the magnitude of total compression. A decreasing compressibility during the consolidation process accelerates the rates of compression and the excess pore pressure dissipation, whereas a decreasing permeability retards them. The influence of the load-increment ratio on the rate of consolidation depends on the ratio of permeability index to compression index. The secondary compression has a significant influence on the compression curves; however, it does not affect the dissipation of pore-water pressure appreciably. A fraction of the excess pore-water pressure equal to the critical pressure ratio dissipates at a rapid rate; the remaining pore pressure dissipates at a slower rate.