Ashtanga Yoga:  The Practice Manual by David Swenson

I use this book all the time!  It has clear, helpful photos and offers modifications for all the postures.  If you're developing a home practice - or think you might one day - this book is a MUST!

Meditations from the Mat

by Rolf Gates

One of my all-time favorites.  My copy is literally falling apart.  The reader explores their own life as they learn more about yoga.  A great addition to any yoga student's library.

Power Yoga

by Beryl Bender Birch

This good book teaches the fundamentals of astanga yoga.  It's written in a very readable way.

The Wisdom of Yoga

by Stephen Cope

This is a beautifully written, accessible description of the Yoga Sutras in action in the lives of one teacher and his friends.

Living Your Yoga

by Judith Lasater

This book was recommended to me by a friend and fellow student.  It's a short collection of essays illustrating how your yoga practice touches all areas of your life.

Beyond Power Yoga

by Beryl Bender Birch

Another one of my favorites!  This book brings you "behind the scenes," explaining how yoga works beyond the poses.  Written so that any student can understand and begin to work with the concepts.  Great book!

Yoga Mala

by Sri K. Pattabhi Jois

This classic is authored by the father of astanga yoga.  No library is complete without a copy.

Light on Yoga by BKS Iyengar

Again, no yoga library is complete without a copy of this classic.  Iyengar is one of the modern fathers of yoga.