The Three Mile Island (TMI) accident represents the only full-scale integrated facility data for a severe nuclear power reactor accident. As a result of this accident, an extensive, worldwide effort was initiated to develop the understanding and analytical tools to analyze severe accidents. The data required to understand and document the accident progression have been extracted throughout the accident recovery and cleanup process. At the same time, several severe accident codes reached a stage of development where a comparison with the actual event could be attempted. A unique opportunity existed, therefore, to benchmark the severe accident analysis computer codes. Such an effort is nearing completion, with the cooperation of the Committee on the Safety of Nuclear Installations, in the form of the TMI Analysis Exercise. The exercise began in October 1987 and is scheduled for completion in early 1990. Some 13 participants, representing 9 countries, are presently involved in this effort. It is hoped that the completion of the exercise will result in an international consensus on code assessment and severe accident predictive capabilities.