A series of surveys sponsored by the National Institute of Justice from 1986 through 1989 and the 1990 Kutztown University survey have tracked the growth of monitoring from a daily census of 95 offenders on electronic monitoring in April 1986 to over 12,000 offenders as of February 1990. Of the 285 public agencies responding to the 1990 overall survey, 214 identified the following as reasons for implementing electronic monitoring: reduction of crowding or reduced incarceration costs; provision of additional or alternative sentencing options; augmentation of supervision, control, or community production; reduction of incarceration; and rehabilitation. The massive growth in the use of electronic monitoring of parole systems since the completion of the 1990 survey appears to be occurring more from the expansion of existing programs than from the initiation of new sites. 11 notes and 4 tables