A number of tables present data on the changing characteristics of high school students taking the American College Testing Program examination (ACT), and on the declining ACT scores, from 1970 to 1975. A brief research review indicates that the observed declines are not merely a result of the tests themselves. The author suggests these explanations: (1) the increased proportion of female test takers, many of whom represent lower academic ability levels; and (2) high school grade inflation, which encourages less able students to perceive themselves as "college material," take the entrance examinations, and perform poorly. The author also concludes that the declines are not due to changes in the performance of racial minorities, since the declines have been steeper for Caucasian students. The declines are also marked for students who plan to attain a Bachelor's degree only. Though a variety of student background and demographic variables exert modest effects on scores, the strongest statistical relationship was found between high school enrollment in academic courses and test scores. The author suggests that the score decline may also be a result of the broader spectrum of students who aspire to college, and that this is acceptable because of the expanded educational opportunity. (Author/GDC)