A simple and rapid laboratory test that uses standard 9.44 cm"(0.03 ft") compacted soil specimens for strength comparisons is presented and discussed. The test gives discrete evaluations of undrained c, þ, and other strength parameters from single soil specimens. The specimens are subjected to vertical compression while confined in a split steel mold, which acts as a spring, so that spreading of the mold pro-vides a measure of lateral stress. Thus, K, or the ratio of soil horizontal to vertical stress, may be continuously monitored and used to obtain strength parameters and moduli as the test progresses. In addition, a direct measure of soil-to-steel friction as a function of normal stress is obtained. The K-test simulates an undrained, rapidfield-loading situation and appears particularly applicable for transportation facilities. This paper presents representative results on several soils, discusses errors in the assumptions, and describes some potential uses of the test for design and control purposes.