The Ames Laboratory Research Reactor (ALRR) was constructed between 1961 and 1965 on a 35 acre open site about 1 1/2 miles from the Iowa State University campus and the rest of the Ames Laboratory facilities. Initial criticality was attained in February and full power in July 1965. Full-time operation was initiated in June 1966. Final reactor shutdown occurred on December 31, 1977, with an accumulation of 1.52 x 10/sup 4/ megawatt days. The reactor decommmissioning program was initiated at that point, and was essentially completed by October 1, 1981. Total radiation exposure for the decommissioning program was 69.4 man-rem distributed among 92 persons. The total cost of the program was 4.335 million dollars. Although the initial intent was to be able to release the facility for unrestricted use on completion of decommissioning, the widely dispersed presence of low-level fixed radioactivity on reactor room surfaces and in imbedded piping resulted in the application of a monitored use criterion.