This paper presents part of the research work being performed under the "International Subgrade Performance Study" sponsored by the Federal Highway Administration (FHWA). The objective of the subgrade study is to define one or more predictive models that will relate rutting to soil type, stress/strain level, and soil moisture conditions. Full-scale instrumented flexible test pavements will be constructed in the Frost Effects Research Facility at the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) and at the Danish Road Institute (DRI). Accelerated loading will be used to simulate traffic, and pavement performance will be measured. As part of the research work, repeated-load triaxial testing of both resilient and plastic properties of the subgrade soils will be performed. Characterization of resilient properties is being done at Cornell University. Special testing equipment and procedures for specimen preparation have been developed. The procedure produces specimens with a uniform density and moisture gradient. The test plan for repeated-load triaxial testing of resilient modulus, and plans for model building from the results are described.