Book excerpt: Teachers make a difference. The success of any plan for improving educational outcomes depends on the teachers who carry it out and thus on the abilities of those attracted to the field and their preparation. Yet there are many questions about how teachers are being prepared and how they ought to be prepared. Yet, teacher preparation is often treated as an afterthought in discussions of improving the public education system. Preparing Teachers addresses the issue of teacher preparation with specific attention to reading, mathematics, and science. The book evaluates the characteristics of the candidates who enter teacher preparation programs, the sorts of instruction and experiences teacher candidates receive in preparation programs, and the extent that the required instruction and experiences are consistent with converging scientific evidence. Preparing Teachers also identifies a need for a data collection model to provide valid and reliable information about the content knowledge, pedagogical competence, and effectiveness of graduates from the various kinds of teacher preparation programs. Federal and state policy makers need reliable, outcomes-based information to make sound decisions, and teacher educators need to know how best to contribute to the development of effective teachers. Clearer understanding of the content and character of effective teacher preparation is critical to improving it and to ensuring that the same critiques and questions are not being repeated 10 years from now.