This book deals with plant growth and development as regulated by hormones. This book deals only with the better known or better studied aspects of plant growth regulation by hormones. The book is written for third and fourth year undergraduates and beginning graduate students who have had basic botany and some introduction to biochemistry and molecular biology. It is designed to complement texts in plant physiology. Like most other text books, it originated because there was no single text that covered the burgeoning field of hormonal and environmental regulation of plant growth that was reasonably up to date. Since then, research in plant growth and development, spurred on by the application of molecular and genetic techniques, has revolutionized our thinking in plant biology. Many other individuals played important roles in completion of this book. Finally, but probably the most important, credit goes to my wife for providing support and encouragement at some of the bleakest moments during the writing of this text.