Developed was a category system for systematic observation of the verbal and non-verbal behavior of high school biology teachers in both classroom and laboratory situations. This system was used to study the similarities and differences existing between the Biological Sciences Curriculum Study (BSCS) and non-BSCS teachers. Individual teachers differed significantly with respect to laboratory management, control, release, scientific process, facilitating communication, and negative affectivity, but no significant differences were found between the two groups. Scientific process for the two groups approaches significance at the .05 level; it was evident from inspection that BSCS teachers were higher in scientific process behaviors than non-BSCS teachers. Findings indicated that non-verbal behaviors influenced the learning situation in some 65 per cent of all teacher behaviors studied. (GR)