INFORMATION ON THE BACKGROUND AND ATTITUDES OF AN EXPERIMENTAL GROUP OF 191 HIGH-POTENTIAL, LOW-ACHIEVING 10TH-GRADE STUDENTS WAS SUPPLIED TO THEIR TEACHERS TO DETERMINE THE EFFECT OF THIS INFORMATION ON THE STUDENTS' PERFORMANCE. TEACHERS OF STUDENTS (114) IN A QUASI-CONTROL GROUP WERE INFORMED THAT THEIR PUPILS HAD TESTED AS UNDERACHIEVERS, BUT NO SPECIFIC DATA ABOUT THE STUDENTS WAS SUPPLIED TO THEM. UNDERACHIEVERS (191) IN A TRUE CONTROL GROUP WERE NOT IDENTIFIED TO THEIR TEACHERS. AN ACHIEVEMENT BATTERY, A SELF-CONCEPT INDEX, AND GRADE POINT AVERAGES WERE USED TO MEASURE THE EFFECT OF THE TEACHERS' KNOWLEDGE UPON PUPIL PERFORMANCE AFTER FIVE SEMESTERS. DATA WAS MADE AVAILABLE ON THE BACKGROUND AND ATTITUDES OF AVERAGE- AND HIGH-ACHIEVING STUDENTS SO THAT THE UNDERACHIEVERS MIGHT BE COMPARED WITH THEM. THE HYPOTHESIS THAT THE EXPERIMENTALS WOULD IMPROVE OVER THE CONTROLS IN ACADEMIC PERFORMANCE AND IN SELF-ATTITUDES WAS NOT CONFIRMED. (LB)