The present study investigated the pattern of relations among the tacit knowledge of high school teachers, their professional development, and their metacognitive knowledge concerning their teaching practices. Two hundred and seventy-nine secondary school teachers of both sexes, between the ages of 30 and 59 years, with teaching experience of between 1 and 19 years, participated in the study. Teachers' tacit knowledge was evaluated through the hypothetical scenarios of the Tacit Knowledge Inventory for High School Teachers (TKI-HS), which has been developed for the estimation of teachers' practical strategies. For the evaluation of teachers' metacognitive knowledge and professional development, self-report questionnaires were administered to the participants. Path analysis indicated relationships between teachers' metacognitive knowledge regarding difficulties in classroom management and in the use of modern methods and technologies on the one hand, and the use of certain tacit knowledge strategies on the other. In addition, teachers' professional development, especially their ability to interact in socially heterogeneous groups, was also found to have an effect on their tacit knowledge strategies.
Keywords: high school teachers; practical intelligence; professional growth.