Book excerpt: In Online Professional Development for Teachers, the authors look closely at exemplary online professional development programs, compare them carefully with one another, and draw helpful conclusions about them--both for those who develop online programs and for teachers and administrators in search of professional development programs that make a difference. How can professional development for teachers be more efficient and effective? This essential question lies at the heart of this timely and useful book. In an era marked by a heightened emphasis on school reform, the education and professional development of teachers is widely regarded as the keystone to educational improvement. Recently a bewildering array of online professional development programs has arisen. But how effective are these programs and how do they compare with one another? A book that brings clarity and insight to this burgeoning and influential field, Online Professional Development for Teachers will be of great value to researchers, policymakers, administrators, and teachers as they work to make the most of online professional development.