This book is the second edition of Design to Test. The first edition, written by myself and H. Frank Binnendyk and first published in 1982, has undergone several printings and become a standard in many companies, even in some countries. Both Frank and I are very proud of the success that our customers have had in utilizing the information, all of it still applicable to today's electronic designs. But six years is a long time in any technology field. I therefore felt it was time to write a new edition. This new edition, while retaining the basic testability prin ciples first documented six years ago, contains the latest material on state-of-the-art testability techniques for electronic devices, boards, and systems and has been completely rewritten and up dated. Chapter 15 from the first edition has been converted to an appendix. Chapter 6 has been expanded to cover the latest tech nology devices. Chapter 1 has been revised, and several examples throughout the book have been revised and updated. But some times the more things change, the more they stay the same. All of the guidelines and information presented in this book deal with the three basic testability principles-partitioning, control, and visibility. They have not changed in years. But many people have gotten smarter about how to implement those three basic test ability principles, and it is the aim of this text to enlighten the reader regarding those new (and old) testability implementation techniques.