Perhaps one of school psychology's greatest "Difference Makers", Dr. James Ysseldyke has been educating school psychologists and researchers for more than 35 years. His research and writing have focused on enhancing the competence of individual students and enhancing the capacity of systems to meet student's needs. Dr. Ysseldyke has directed two major research centers and multiple research projects focused on assessment and the use of assessment information to make decisions about students. He will summarize major findings from 35 years of research and discuss implications for policy and practice. Anticipated future directions also will be discussed.