Americans have been exposed to increased levels of mass violence during the past decade. School violence, shootings in the workplace, and terrorist acts both here and abroad--all have affected individuals, families, communities, and our country. This report addresses the urgent need to evaluate the various psychological interventions that are increasingly among the first responses to these traumatic events. At a workshop held from October 30 to November 1, 2001, 58 disaster mental health experts from six countries were invited to address the impact of early psychological interventions and to identify what works, what doesnt work, and what the gaps are in our knowledge. Prior to the workshop, leading mental health research clinicians from the United States, Australia, and the United Kingdom prepared a review of the published, peer-reviewed literature (references appear in Appendix I). The report emphasizes that although more research is needed, existing data, including studies of other kinds of traumatic events, as well as clinical experience, provide useful guidance to the mental health community in responding to mass violence. The report is targeted to those who deliver psychological interventions to emotionally distressed persons following mass violence, to those who research these issues, and to employers who want to help workers who have experienced this type of emotional trauma. (Contains 146 references, 10 tables, and 9 appendixes.) (GCP)