The Transfer Procedure Test is taken by children around 11 years of age who wish to attend grammar schools in Northern Ireland. It is a high stakes test in that children are only allowed one attempt and their performance determines their future schooling in a manner that is not of their choice or of their parents. Candidates usually take two test forms, with a supplementary test available for those, who for one reason or another, do not have both test scores. This report describes the largest independent study of the Transfer Procedure Test ever conducted. Samples of test scripts used as practice tests in 52 primary schools were analyzed to see if the test functions effectively in enabling the selection of students for grammar school places. The samples used for the analyses consisted of 1,288 students (test 1), 1,270 students (test 2), and 623 students (supplementary test). The test is designed to measure mathematics, English, and science achievement, and the addition of these scores in the Transfer Procedure Test is questionable. Because the test does not measure any single attribute of candidates, it cannot be used as a proxy for any particular attribute. The test would be perceived as easy by many students, since more than 65% answered more than 70% of the questions correctly. The easiness is a serious design flaw, as children would have been awarded a D with a 70% score, and it is difficult to justify failing a student who has answered so many items correctly. The tests were found to be highly reliable, but the published information on the test does not meet the requirements of international standards on education testing, nor does it supply reliability and validity information. Information is provided about the predictive ability of the test for later student achievement. (Contains 22 tables, 3 figures, and 26 references.) (SLD)