HISTORICALLY, ASSASSINATION WAS AN ACCEPTED HAZARD OF THOSE IN POWER OR OF THOSE WHO POSED A THREAT TO THE ESTABLISHED ORDER. THE TERM 'ASSASSIN' DERIVED FROM A CRUSADER CORRUPTION OF THE ARABIC 'HASHASHIN' OR USERS OF HASHISH. THE ASSASSIN DIFFERS FROM THE TERRORIST (WHOSE PURPOSE IS TO CREATE CHAOS) AND THE MURDERER (WHO KILLS OUT OF UNREASONING PASSION) IN THAT HE DELIBERATELY AND CALCULATINGLY SETS OUT TO TAKE A LIFE. MOREOVER, ASSASSINS USUALLY ACT ALONE, WITHOUT BELONGING TO AN ORGANIZED GROUP. THE IMPACT OF ASSASSINATIONS ON SOCIETY CAN BE INCALCULABLE. FOR INSTANCE, THE MURDERS OF THE FRENCH FOREIGN MINISTER AND THE KING OF YUGOSLAVIA IN 1934 ASSURED FACTIONALISM IN YUGOSLAVIA AND THE ASCENDANCY IN FRANCE OF A POLITICIAN NOTED FOR HIS APPEASEMENT OF NAZI GERMANY. PSYCHIATRIC DIAGNOSES OF ASSASSINS HAVE SUGGESTED THAT MANY OF THESE PERSONS HAVE SCHIZOID PERSONALITIES OF A PARANOID TYPE. THUS, THE MURDERS OF THE KENNEDY BROTHERS, ABRAHAM LINCOLN, WILLIAM MCKINLEY, JAMES GARFIELD, AND THE ATTEMPTS ON THE LIVES OF OTHER AMERICAN POLITICAL FIGURES, SUPPOSEDLY WERE ACTS OF DERANGED INDIVIDUALS. THE CASE STUDIES OF LEE HARVEY OSWALD AND SIRHAN SIRHAN, DETAILED HERE, SHOW FURTHER THAT THESE ASSASSIONS SHARED A BELIEF THAT THEY COULD ALTER WORLD CONDITIONS WITH A GUN. INNOVATIONS IN ASSASSINATION METHODS (I.E., THE LETTER BOMB) AND PREVENTATIVE METHODS ARE NOTED. AN INDEX AND PHOTOGRAPHS ARE INCLUDED. (WJR)