In this book, Dr. Li and his author team plan to emphasize why mouse models are useful in vivo systems for understanding disease mechanisms and developing therapeutic strategies in blood cancers. The authors do not intend to cover all types of blood cancers; instead, they will focus on some major ones such as leukemias and lymphomas. However, the authors will try to cover as much as they can the cancer types and point out that many blood cancers need to be studied in mouse disease models although they are still not available at present. A major focus in the book will be to show what we can or cannot learn from mouse disease models and to also show the critical contributions of mouse models in therapeutic drug development.