The Low-Level Waste Data Base Development—EPICOR-II Resin/Liner Investigation Program—funded by the U.S. Nuclear Regulatory Commission (NRC) is obtaining information on performance of radioactive waste in a disposal environment. This paper presents a description of the field testing and gives preliminary findings. Solidified ion-exchange resin materials from EPICOR-II prefilters used in the cleanup of the Three-Mile Island Nuclear Power Station are being field tested to develop a low-level waste data base and to obtain information on survivability of waste forms composed of ion exchange media loaded with radionuclides and solidified in matrices of cement and Dow polymer. Emphasis is placed on evaluating the requirements of 10 CFR 61 “Licensing Requirements for Land Disposal of Radioactive Waste” by obtaining data on performance of waste in a disposal environment using lysimeter arrays at Oak Ridge National Laboratory (ORNL) and Argonne National Laboratory in Illinois (ANL).