The Adaptive School: A Sourcebook for Developing Collaborative Groups (2nd Ed.), by Robert J. Garmston and Bruce M. Wellman (2009)
For a wealth of specific tools you can use immediately to develop collective understanding, make decisions, respond to conflict, and develop high performance groups, turn to this authoritative guide.

Content-Focused Coaching: Transforming Mathematics Lessons, by Lucy West and Fritz C. Staub (2003)
Content-Focused Coaching (CFC) is a long-range professional development practice in which coaches work individually or with groups of classroom teachers to design, implement, and reflect on rigorous, standards-based lessons that promote student learning. Authored by two educators closely involved with the design of CFC, this book is for K-8 staff developers, teacher leaders, administrators, and others interested in improving mathematics education.

Cultivating a Math Coaching Practice: A Guide for K-8 Math Educators, by Amy Morse (2009)
Given the current demands of a math teaching practice, this case-based resource helps math coaches, prospective coaches, and administrators develop their knowledge of math content, hone their coaching skills, and enhance their ability to provide professional development for teachers in Grades K-8.

The Math Coach Field Guide: Charting Your Course, edited by Carolyn Felux and Paula Snowdy (2006)
The role of a math coach is demanding and often undefined. In this collection of essays, veteran math coaches share their expertise, providing glimpses into the unique trials, false starts, and successes they have faced in their positions. The authors ask and answer such questions as: What makes an effective math coach? What are helpful strategies for supporting both eager and reluctant teachers? and What pitfalls do math coaches encounter and what can they do about them?
Written by coaches for coaches, this book is also an invaluable resource for teacher leaders, school administrators, and mathematics supervisors.

Mathematics Coaching Handbook: Working with Teachers to Improve Instruction, by Pia M. Hansen (2009)
Help prepare and support effective math content coaches with this guide. It provides insight into the leadership skills necessary to mentor other teachers, establish collaborative teacher teams, and influence school culture positively.