This study was undertaken at Knox College (Galesburg, Illinois) to explore the effectiveness of one way of preparing in-service teachers in transformational grammar. The method involved two phases: (1) the training of four high school English teachers, in one school district, in transformational grammar, and (2) the production of a series of introductory lectures for all district English teachers of grades 7-12. Training in the first phase was intensive, involving outside reading and 10 two-hour sessions. At the end of the seminar, each teacher taught a unit in transformational grammar and was video-taped teaching part of the unit to one class. The second phase was made up of four one-hour lectures and was meant to provide only a very general picture of the material. Effectiveness of the program was measured by pre- and post-tests for seminar participants and by questionnaires distributed to all teachers attending the second-phase lectures. The intensive in-service education course was judged successful, but the lecture series, although beneficial, was considered generally inadequate. (Appendices include the test and reading list for the seminar.) (Author/LH)