The consolidation behavior of soils is usually predicted by making use of the convectional theory of consolidation proposed by Terzaghi.Laboratory observations of the consolidation behavior exhibit discrepancies between the theory and the results. These discrepancies are usually attributed to the secondary effects that occur during primary consolidation. On the other hand, Terzaghi’s theory presupposes the constancy of permeability and compressibility of the soil. In this study, the effect of variable permeability and compressibility on the consolidation behavior is investigated. For this objective, mathematical treatment of the behavior is presented. Subsequently, laboratory consolidation tests with mid-plane pore pressure measurements are conducted on soft, remolded, pre-consolidated and undisturbed samples of clay. The test results, when compared with the theoretical findings, indicate that most of the inherent discrepancies may be explained via the use of the theory developed in this study.