The American Nurses Association, American Psychiatric Nurses Association and the International Society of Psychiatric Mental Health Nurses worked together with nurses from across the nursing profession to develop Psychiatric–Mental Health: Scope and Standards of Practice, 3rd Edition. It is the definitive and up-to-date delineation of psychiatric–mental health nursing, articulating the competent level of nursing practice and professional performance of all PMH registered nurses, whatever their practice level or setting. The publication’s scope of practice addresses what is expected of all psychiatric–mental health nurses, specifying the who, what, where, when, why, and how of their practice. The detailed discussion of that scope of practice provides the context needed to understand and use the standards, presenting the underlying assumptions, characteristics, environments and settings, education and training requirements, key issues and trends, and ethical and conceptual bases of the specialty.