The program permanently altered environmental conditions under which reports were prepared to facilitate performance. Police officers, who had previously prepared reports without assistance, visited the case preparation room to prepare reports with assistance from officer personnel. Compared to reports prepared without assistance, reports prepared in the case preparation room documented more case elements required by the State legal code for criminal prosecution, were completed in fewer days following arrests, and received higher ratings from assistant district attorneys. Operation of a permanent program available to approximately 945 officers provided a practical solution to improving the preparation of criminal investigation reports. Seven references are given. (Author abstract modified)