The author argues that despite the vast proliferation of scientific research, our understanding of dyslexia is marked by serious weaknesses of conceptualization, definition, and operationalization that are not only unscientific but also result in impoverished practice in schools, social inequity in both understanding and provision for many struggling readers, and ultimately, reduced life chances for millions of students worldwide. Key to this problem is the inconsistency of the use of the term "dyslexia" in both scientific research and clinical and educational practice. Four different, common conceptions of dyslexia are outlined, and the implications that each of these have for work with struggling readers are discussed. Whereas it is often claimed that scientific understandings, derived from genetics, neuroscience, and cognitive science, enable clinicians to validly identify, from within a larger group of poor readers, those individuals with dyslexia, the author shows this to be not only misleading but also potentially deleterious to broader inclusive practice. The author argues that the seemingly scientifically based construction of the dyslexic individual, often buoyed by vested interests, typically favors more socially privileged students and often undermines attempts to identify and help all of those who struggle to learn to read. Common responses by proponents to challenges to the dyslexia construct are outlined and discussed. In conclusion, the author argues that scientists, researchers, clinicians, and educators have a responsibility to address and confront the real-world consequences of much science but little wisdom in the field of reading disability.