The York Region Board of Education in Ontario, Canada, screens students for giftedness in grade 3. This report analyzes data produced in the 1986-87 screening procedure, involving approximately 3,400 students. The report begins with a review of procedural changes that were designed to make the screening more effective and efficient than earlier study cycles. Then the results of the most recent screening are examined, with the finding that scores on the Otis-Lennon Mental Abilities Test and Raven's Standard Progressive Matrices were better predictors of giftedness than parent or teacher recommendations and better than the testing of siblings of pupils previously identified as gifted. The data analysis reviewed the following specific issues: (1) errors in calculating or recording data; (2) male and female performances on the screening procedures; (3) effectiveness of the screening of French immersion pupils; (4) effectiveness of the screening of pupils with gifted siblings; (5) effectiveness of the Teacher Checklist as an initial screen; and (6) effectiveness of peer nomination as an initial screen. The report concludes with recommendations to further increase the effectiveness and efficiency of the screening procedures. (JDD)