IN THE COURSE OF CONDUCTING EXAMINATIONS OF DOCUMENTS INVOLVED IN THE THEFT AND FORGERY OF UNITED STATES TREASURY CHECKS, SAVINGS BONDS, AND RELATED DOCUMENTS, THE IDENTIFICATION BRANCH OF THE UNITED STATES SECRET SERVICE HAS FOUND A NEED TO ESTABLISH A REFERENCE FILE OF CHECKWRITER IMPRESSIONS AND TO CONDUCT RESEARCH CONCERNING THE WORK OF THESE MACHINES. THIS FILE CURRENTLY INCLUDES DOMESTIC IMPRESSIONS DATING BACK TO 1907, AS WELL AS SOME FOREIGN IMPRESSIONS. ALL OF THE CHECKWRITER COMPANIES IN THE UNITED STATES, AS WELL AS SOME LARGE FOREIGN COMPANIES, HAVE BEEN VISITED OR CONTACTED. THIS PAPER REPORTS ON THE INFORMATION THAT HAS BEEN OBTAINED, INCLUDING DATA ON MANUFACTURERS AND THE MODELS THEY PRODUCED; COMPONENTS OF CHECKWRITERS WHICH HAVE A BEARING ON THE CLASSIFICATION OR IDENTIFICATION OF AN IMPRESSION; AND THE TWO PROCESSES UTILIZED IN APPLYING A CHECKWIRTER IMPRESSION TO THE PAPER SURFACE. ALSO CONSIDERED ARE THOSE CHANGES IN CHECKWRITER MODELS OVER THE YEARS WHICH MAY BE OF ASSISTANCE IN ESTABLISHING THE AGE OF THE MACHINE USED. (AUTHOR ABSTRACT MODIFIED)...ELW