Most principals are aware that the No Child Left Behind Act of 2001 makes it mandatory for school leaders who depend on federal funding to select and implement programs that are based on scientific research. This publication reviews five documents that offer insights into what is meant by scientifically based research and help school leaders evaluate the scientific basis of practices and programs. In Senate testimony, Grover J. Whitehurst stresses the need for increasing the amount of scientific research in education. A report by the Comprehensive School Reform Program Office provides school leaders with guidance on the use of scientific research in initiating comprehensive reform efforts. In "Scientifically-Based Research," Stephen Raudenbush anticipates and addresses questions that educators might have about the nature and implications of scientific research in education. Evelyn Jacob and C. Stephen White edited a special theme issue of "Educational Researcher" on scientific research in education. (RT)