Carolyn M. Callahan is Commonwealth Professor Emeritus of Education at the University of Virginia. She has been a principal investigator on projects of the National Research Center on the Gifted and Talented for more than 20 years. She has published more than 200 refereed articles and 50 book chapters across a broad range of topics on gifted education. She is a Past-President of The Association for the Gifted and the National Association for Gifted Children and co-editor of Critical Issues in Gifted Education. Holly L. Hertberg-Davis is an educational consultant specializing in differentiation of instruction, advanced curriculum, and professional development.