This paper describes a triaxial-vane apparatus constructed at the Division of Building Research, National Research Council of Canada, Ottawa. A series of tests was conducted on a soft marine clay from South Gloucester, Ontario. Various consolidation pressures were used to study the effect of pressure on vane strength. The test results show that the vane strength is relatively insensitive to a change in vertical consolidation pressure only, but increases steadily with increase in the all-around or horizontal consolidation pressure. This phenomenon is explained using an analysis that incorporates strength anisotropy. The practical implications resulting from this study are also discussed.