The purpose of this discussion is to describe and contrast several tenets of scientific behavior and practice with the behaviors and practices associated with advocacy. We argue that scientists must focus their efforts on solvable problems, consider their efforts to be uncertain, and present their findings dispassionately, so that others might judge the evidence for themselves. Advocates, in contrast, must confront the problems facing the people for whom they have concern over whether the problems appear to be solvable or not. Furthermore, advocacy requires a certainty of conviction that leads to the promotion of particular positions and their adoption by others. We suggest that although special education's roots are more closely aligned with advocacy than with science, its future depends on its ability to adopt a more fully scientific approach to practice. We conclude with a discussion of how the assignment of test accommodations to students with disabilities illustrates the tension between science and advocacy.