A study was conducted (as one aspect of an intervention program in Head Start classes) to explore the consequences of the interjection of the observer into the classroom, with particular emphasis on the teacher's reactions to this attempt to supply a dimension of understanding about the classroom to supplement his own perspective. In a case study approach, four teachers were selected on the grounds of their divergent styles and background. Procedures included observation of teachers' styles (using Beller scales to determine the sensitivity of the teacher to the psychological and interpersonal needs of children in the classroom) and interviews with teachers and observers on the nature of interaction between teachers and observers. Conclusions drawn from the four case studies: Each teacher resisted the activities of the observer and established barriers to the utilization of the observers as a source of information about the classroom. In her own way, each teacher was able to so vastly delimit the activities of the observer that few meaningful interactions between teacher and observer occurred. Unaware of the issues which their presence raised for teachers, observers were at a disadvantage in their capacity to contribute to the educational issues of the classroom. By retaining her authority over the classroom, the teacher was able to determine the conditions which could not be challenged, changed, or expanded by the observer. (Author/JS)