This chapter discusses the history and function of the psychiatric report. The contemporary view of written forensic reports is closely related to the development and contributions of professional organizations. Recent authors describe the primary function of the psychiatric report as the effective communication of information. The widespread introduction of the written psychiatric report in the twentieth century has been followed by professional, judicial, and academic input as to what structure the report should have and what its function should be. That function has come to be seen as both broader and deeper than the simple communication of an opinion. Broader, because the report serves other functions too, including preparing the ground for oral testimony. Deeper, because it is now clear that the provision of even the most basic elements of a report, including a narrative account of events, requires more rigorous description and analysis than it has so far received.