Book excerpt: The Total School Cluster Grouping Model is a specific, research-based, total-school application of cluster grouping combined with differentiation, focused on meeting the needs of students identified as gifted while also improving teaching, learning, and achievement of all students. This revised and updated second edition of Total School Cluster Grouping and Differentiation includes rationale and research followed by specific steps for developing site-specific applications that will make the important art of differentiation possible by reducing the range of achievement levels in teachers' classrooms. Materials to support staff development—including powerful simulations, evaluation, management, special populations, differentiation strategies, social and emotional needs, and recommended materials—are included.