In response to a series of national policy reports regarding what has been termed the "quality chasm" in health and mental health care in the United States, in January 2003, the American Association for Marriage and Family Therapy convened a task force to develop core competencies (CC) for the practice of marriage and family therapy (MFT). The task force also was responding to a call for outcome-based education and for the need to answer questions about what marriage and family therapists do. Development of the CC moves the field of MFT into a leading-edge position in mental health. This article describes the development of the CC, outcomes of the development process for the competencies, and recommendations for their continued development and implementation.