This paper presents part of the research work being performedunder the "International Subgrade Performance Study"sponsored by the Federal Highway Administration (FHWA). The objectiveof the subgrade study is to define one or more predictive modelsthat will relate rutting to soil type, stress/strain level, andsoil moisture conditions. Full-scale instrumented flexible testpavements will be constructed in the Frost Effects Research Facilityat the U.S. Army Corps of Engineers Cold Regions Research andEngineering Laboratory (CRREL) and at the Danish Road Institute(DRI). Accelerated loading will be used to simulate traffic, andpavement performance will be measured. As part of the researchwork, repeated-load triaxial testing of both resilient and plasticproperties of the subgrade soils will be performed. Characterizationof resilient properties is being done at Cornell University. Specialtesting equipment and procedures for specimen preparation havebeen developed. The procedure produces specimens with a uniformdensity and moisture gradient. The test plan for repeated-loadtriaxial testing of resilient modulus, and plans for model buildingfrom the results are described.