The purpose of this study is to investigate the primary factors which control the engineering behavior of silts. The methods of classifying silts at present do not provide much basis to infer how silts will behave in the field for design purposes. In the course of this research study, series of UU and CU triaxial test results of different silt samples were gathered to investigate the factors that control the strength parameters of silts. Effective and total stress strength interpretation were done on the test results. The effective stress friction angle were evaluated using the CU triaxial test results. Undrained strength parameters were determined from the CU and UU triaxial test results, and comparison were performed using the undrained strength ratio S_u/p. Silt samples which exhibit dilative behavior during undrained shear make it difficult to define failure. Because of this behavior, the test results were interpreted using different failure criteria to assess the effective stress friction angle and the undrained strength parameters. Test results indicate that the effective stress friction angle can be evaluated using the CU triaxial test will little uncertainty. The undrained shear strength of silt samples are influenced by the type of failure criteria. The results indicate that a unique undrained shear strength can not be determined because the samples get stronger with increasing strain. A reliable method of evaluating the undrained shear strength of silt samples is to determine the relationship between the undrained strength ratio and the changes in pore pressure. / Master of Science