The extent to which teachers use the services provided by The School Television Service (STS), the instructional division of Channel 13/WNDT (New York), was studied. After determining that the STS is representative of many broadcast instructional television agencies, a five-page questionnaire was administered to a sample of 1037 teachers whose school districts participated in STS. The sample provided 752 usable responses. Results showed that a majority (57.9 percent) of the respondents used the program series regularly (at least several times a semester), and that the average regular use of the program series was 1.8 program series per teacher per semester. Three conditions were found to be statistically associated with the number of series a teacher uses: the storage location of the television set, the teacher's professional preparation, and the grade levels concerned. (Author/SP)