An assessment of the stress of junior high/middle school (JH/MS) can be made by comparing overall behavior and academic student patterns in JH/MS with those in elementary school (ES), and by evaluating the differential educational consequences experienced by JH/MS students who had varying degrees of maladjustment in ES. Specific numeric data indicate that the environment is far more open, combative, frightening, impersonal, and academically taxing in JH/MS than in the ES. Partly as a result, suspensions, unexcused absenteeism, and grade failure occur at a much greater overall rate in JH/MS. Also, the immediate aftermath of these school adversities is significantly more deleterious in JH/MS than in ES. An analysis of the differential outcome data reveals that JH/MS students who had prominent ES maladjustments have a 5-13-fold greater rate of grade failure, suspension, and undue absenteeism than do students without such ES difficulties, and that generally students without major ES malajustment patterns continue to perform well after their entry to secondary school. In effect, then, JH/MS is primarily a stressful environment for students who are vulnerable on entry.