The title of this book derives from its central chapter, written by Lily Wong Fillmore and Catherine E. Snow, demonstrating that all teachers need deep, broad knowledge about language to support their students' language and literacy development. Five commentaries on that chapter from the perspective of early childhood education, teacher certification, and teacher preparation and professional development point out the value and the challenges of improving educators' understanding about language.

This volume is intended for educators in teacher preparation and professional development, for administrators and policy makers, and for teachers wanting to know more about the role that language plays in linguistically and culturally diverse schools.