Radiochemical, elemental, and particle size analyses have been performed on samples collected from the Three Mile Island Unit 2 reactor and auxiliary buildings. Measurements of the airborne concentration of iodine several days after the accident indicated that the equilibrium airborne concentration was at a maximum of 0.03% of core inventory inside the reactor building (RB), evidently as organic forms. Iodine was released to the reactor coolant during the accident and ∼14% of the core inventory of iodine was in solution in the water in the RB basement. Between 8 and 100% of the core inventory of iodine was accounted for in the sediment distributed over the RB basement floor. About 47% of the core inventory of cesium was released from the core. The majority of the released cesium was in solution in the water in the RB basement. Antimony and ruthenium were retained in the core, associated with stainless steel materials. Strontium and cerium were retained in the core in the forms of refractory oxides. Fuel and control rod elements found in the reactor coolant drain tank were evidently transported away from the core as condensed vapors in the form of hydrosols.