Teachers in Ireland (n = 170) rated students (n = 2,617) on IQ, mathematics, and English, as well as on 12 social and academic classroom behaviors. Factor analysis oflQ, mathematics, and English standardized test scores, together with the 15 teacher ratings, showed that there is overlap between ratings and test results but that the information obtained is not redundant. Three factors were identified: one was comprised primarily of the social behaviors; a second was comprised of the academic classroom behaviors and teacher ratings on IQ, mathematics, and English; and the third was comprised of the test scores in IQ, mathematics, and English together with the corresponding teacher ratings.The question under investigation, the relationship of teacher ratings to standardized tests, goes back to Binet. However, opportunity for new illumination into this area was provided by a nationwide, longitudinal, societal experiment conducted in the Republic of Ireland to assess the impact of introducing standardized testing on various populations, particularly students and teachers (Airasian, Kellaghan, & Madaus, 1971). For the present study, 170 fifth-grade teachers were asked to provide ratings for each of their students on a variety of behaviors using a 5-point rating scale. Just prior to making their ratings, teachers administered standardized tests of intelligence, Portions of this paper were presented at the annual conference of the National Council on Measurement in Education, Toronto, 1978.