For the past decade, the first edition of this unique book has lighted the way for those seeking to navigate the perilous shoals of providing mental health services in jails and prisons. These guidelines have been used and cited extensively in many contexts: educational, planning, and legal. They also have been used by surveyors and monitors of correctional facilities. Since the publication of the first edition, American jails and prisons have seen many changes, including considerable litigation, the development of consumer groups, and the creation of some exemplary programs. However, there has also been a dramatic increase in the population of U.S. jails and prisons. In September 1989, when the first edition of these guidelines was published, our nationAs jails and prisons held an estimated 1.2 million men and women. This number is now 1.8 million. Many studies have consistently demonstrated that about 20% of these inmates have serious mental illnesses, and as many as 5% are actively psychotic. With upward of 700,000 men and women entering the U.S criminal justice system each year with active symptoms of serious mental disorders, with 75% of these people having co-occurring substance abuse disorders, and with these persons likely to stay incarcerated four or five times longer than similarly charged people without mental disorders, what are our duties and responsibilities? How do we live up to our personal moral principles, our professional ethics, and our public service obligations in the face of these overwhelming numbers? This is the question to which this book is addressed. This book is intended both to prod to action and to provide comprehensive guidance on how to fulfill these responsibilities to ourselves, our profession, and these badly underserved patients. We have the technologies for treatment and the knowledge and the skills, yet limited resources and public and professional resistance often impede appropriate response. We believe that these guidelines can help overcome many of these sources of resistance through informed action. More active involvement of our profession, as described in these guidelines, is needed, is possible, and will make a difference.