THE PURPOSE OF THIS STUDY WAS TO INVESTIGATE THE RELATIONSHIP BETWEEN CHANGES IN OPENNESS TO EXPERIENCE OF STUDENT TEACHERS AND THE OPENNESS OF THEIR COOPERATING TEACHERS AND COLLEGE SUPERVISORS. THE STUDENT TEACHERS COMPLETED THE COLLEGE STUDENT PROBLEMS Q-SORT TO MEASURE THEIR OPENNESS AND CHANGES IN OPENNESS DURING STUDENT TEACHING. COOPERATING TEACHERS AND COLLEGE SUPERVISORS COMPLETED THE TEACHERS PROBLEMS Q-SORT AND THE COLLEGE TEACHER PROBLEMS Q-SORT TO MEASURE THEIR OPENNESS CHARACTERISTICS. THE STUDY INDICATED THAT NEGATIVE CHANGES IN OPENNESS OCCURED IN THE STUDENT TEACHERS DURING THE STUDENT TEACHING PERIOD. THE SIGNIFICANT NEGATIVE CHANGES IN OPENNESS AMONG STUDENT TEACHERS WERE GREATER FOR THOSE WHO WERE MORE OPEN TO EXPERIENCE AT THE BEGINNING OF STUDENT TEACHING. THE NEGATIVE CHANGES IN THE STUDENT TEACHERS WERE RELATED SIGNIFICANTLY TO THE OPENNESS OF THEIR COOPERATING TEACHERS BUT NOT TO THE OPENNESS OF THEIR COLLEGE SUPERVISORS. CHANGES IN OPENNESS OF STUDENT TEACHERS WERE SIGNIFICANTLY RELATED TO OPENNESS QUALITIES OF THE COOPERATING TEACHERS BUT NOT TO THE PERCEIVED QUALITIES. HOWEVER, NO SIGNIFICANT RELATIONSHIPS IN CHANGE OF OPENNESS OF STUDENT TEACHERS OCCURRED WHEN THESE CHANGES WERE EXAMINED AS FUNCTIONS OF THE ORIGINAL DEGREE OF OPENNESS OF THE STUDENT, HIS COOPERATING TEACHER, OR HIS SUPERVISING TEACHER. (PM)