A study involving 20 British teachers assessed the use of micro-teaching techniques in the training of oral assessors (raters) of students. The study was designed to: measure the efficacy of a training program versus that of a sensitization program, examine methodologies associated with micro-teaching as applied to specific in-service teacher training, and draw conclusions and provide recommendations about the means by which oral assessors may be trained in the future. After a 1979 pilot study, a full study design was implemented to assess the areas of structure, reinforcement, pauses and questions, process indications, and specific skills of oral assessors. Videotapes of subsequent oral assessment interviews between teachers trained during the study and students were rated by six experts. Results indicate that: (1) the micro-teaching experience produces a "transfer of learning" effect that is able to change the behavior of experienced professionals; (2) micro-teaching techniques could be reconstructed as a learning package for in-service training of teachers; and (3) most of the teachers in the micro-teaching group significantly improved their interviewing skills. A bibliography of micro-teaching guides and studies is appended. (TJH)