DATA SOURCES WERE (1) THE RISKS INTERNATIONAL DATA BASE WHICH USED GOVERNMENT, POLICE, AND PRESS REPORTS TO ASSEMBLE DATA FROM NONCOMMUNIST COUNTRIES THROUGHOUT THE WORLD, AND (2) THE 1977 RUSSELL-MILLER SURVEY OF 350 MEMBERS OF 18 GROUPS SPECIALIZING IN URBAN TERRORISM. THE TWO SOURCES PRODUCED SIMILAR FINDINGS. A TYPICAL TERRORIST COMES FROM A WEALTHY MIDDLE OR UPPER CLASS FAMILY, USUALLY A PROFESSIONAL FAMILY. MOST TERRORISTS ARE MALES BETWEEN 22 AND 25 YEARS OF AGE, ALTHOUGH THE JAPANESE RED ARMY AND TWO GERMAN GROUPS HAVE OLDER MEMBERS, AND MOST ARRESTED PALESTINIANS ARE IN THEIR LATE 20'S. IN THE PAST SEVERAL YEARS, THE AGE OF BOTH MALE AND FEMALE TERRORISTS HAS BEEN DROPPING. LEADERS ARE OLDER THAN THE OTHER MEMBERS. EXCEPT IN WEST GERMAN AND PALESTINIAN GROUPS, WOMEN PERFORM MAINLY SUPPORT FUNCTIONS. MOST TERRORISTS ARE UNMARRIED AND HAVE UNIVERSITY TRAINING. COMMON EDUCATIONAL BACKGROUNDS INCLUDE SOCIAL SCIENCES, LAW, AND JOURNALISM. MANY OLDER MEMBERS HAVE BEEN TRAINED IN OR PRACTICED PROFESSIONS SUCH AS MEDICINE, LAW, ENGINEERING, AND TEACHING. THE UNIVERSITIES ARE THE MAIN RECRUITING GROUNDS FOR TERRORISTS. MOST TERRORISTS ARE EITHER NATIVE TO OR RESIDENTS OF THE AREAS IN WHICH THEY OPERATE. MOST LACK CLEARLY DEFINED POLITICAL PHILOSOPHIES OR DEEP UNDERSTANDING OF DOCTRINE. THEIR POLITICAL VIEWS ARE BASED LOOSELY ON THOSE OF MARX, LENIN, TROTSKY, MARIGHELLA, AND OTHERS. THE GROUPS WITH POPULAR BASES (PROVISIONAL IRISH REPUBLICAN ARMY, BASQUE GROUPS, AND PALESTINIANS) ARE MOST LIKELY TO BE INFLUENTIAL IN THE NEXT DECADE. FOOTNOTES WHICH INCLUDE REFERENCES ARE INCLUDED. FOR A RELATED ANALYSIS OF FEMALE TERRORISTS SEE NCJ-63617. (CFW)