To evaluate the usefulness of standardized achievement tests in assessing pre-university academic achievement and aptitude, the Council of Ontario Universities administered tests to incoming freshmen at four Ontario universities, and also examined their high school and subsequent university performance. The tests were designed to measure achievement in English and Mathematics; a writing sample was also taken. The tests used were evaluated for technical quality and validity. It was generally concluded that the tests utilized were found to have generally satisfactory technical qualities, and their utility in evaluating present ability and predicting future performance was comparable to those found in similar studies, that these tests would be useful for selection decisions in the absence of data on students' previous year performance, and that the addition of test scores to students' high school performance data would add only slightly to the efficiency of student selection data. It was further concluded that high school marks, despite their deficiencies, remain the best predictors of university success. Appendices include tables that summarize the findings. (Author/PHR)