Description of Admatch, a set of computer programs for matching geographic codes from a reference file to local data records that contain house addresses. The geographic codes may include zip codes, census tracts, congressional districts, and marketing areas. Admatch requires two machine-readable files: a local data file and a reference file. The preprocessing program uses expandable tables that allow variations in street name configurations or alternative spellings of street or street type. The matcher program specifies the level of discrepancy that can exist between the reference file and the data file and still permit the record for the data file to be matched. The postprocessor program combines rejects from the preprocessing step with the accepted records from the matching step. Discussion covers the role that RAND has played in testing and developing the Admatch programs, defines the equipment, and forecasts applications to urban studies. 13 pp.