During the past 30 years, pavement engineers have increasingly used the elastic layered system theory to predict the physical response of pavement structures in order to determine a proper pavement thickness. The 1986 AASHTO Guide for Design of Pavement Structures has adopted resilient properties in its pavement design. The committee for this Guide recognized that many state highway agencies do not have the proper equipment to determine the resilient modulus. In the Design Guide, correlation of the resilient modulus with the California bearing ratio and the R-value are given. However, these correlations are general in nature and can be used temporarily and only for certain types of soils. The committee has recommended that states develop their own correlations. During this research study, attempts were made to find a correlation between the resilient modulus and the R-value for Colorado soils. To accomplish this task, an extensive laboratory testing program was conducted and the following correlation was established: resilient modulus equals 3500 plus 125 times the R-value. Based on the results of this study, this correlation was established for Colorado soils. Verification of this correlation by additional tests on high quality subgrade (i.e., A-1-b or better) will be needed. After verification, attempts will be made to incorporate this finding in the current CDOH Pavement Design Procedures.