FIRST, CHARACTERISTICS OF REVOLUTION ARE DELINEATED: A PROCESS IN WHICH THE POLITICAL DIRECTION OF A STATE BECOMES DISCREDITED IN THE EYES OF THE POPULATION, A CHANGE OF GOVERNMENT AT A DEFINITE POINT IN TIME BY USE OR THREAT OF FORCE, THE PROGRAM OF CHANGE IN POLITICAL OR SOCIAL INSTITUTIONS INDUCED BY THE REVOLUTIONARY EVENT, AND A POLITICAL MYTH THAT GIVES STATUS TO THE POLITICAL LEADERSHIP EMERGING FROM THE TRANSITION. THEN THESE CHARACTERISTICS ARE USED IN CONSTRUCTION OF THE MODEL. THE MODEL RECOGNIZES THAT THE ESSENTIAL DIFFERENCE BETWEEN A SUBREVOLUTIONARY AND REVOLUTIONARY EVENT IS THE SUCCESSFUL TRANSFER OF POWER USING FORCE FROM OUTSIDE THE LEGITIMATE STATE. THE FORCE MAY BE DIRECTED AGAINST THE EXECUTIVE, AGAINST THE CAPITAL, OR AGAINST THE GOVERNMENT AS A WHOLE, BUT IT MUST INVOLVE A SUFFICIENT QUANTITY OF VIOLENCE (AND CORRESPONDING RESISTANCE) TO BE CLASSIFIED AS A REVOLUTION. FURTHERMORE, THE REVOLUTIONARY DIRECTORATE MUST BE ABLE TO BRING EXCESS FORCE UNDER CONTROL AT THE CRITICAL TIME OF TRANSITION. THE MODEL WITH ITS SEGMENTS FOR REVOLUTION IN VARYING SOCIAL SITUATIONS AND QUANTIFICATION METHODS IS TESTED, AND FOUND TO BE VIABLE, IN A CASE STUDY OF GUATEMALA BEFORE BEING APPLIED AS THE BASIS OF A STUDY OF REVOLUTIONARY MOVEMENT IN THE 20TH CENTURY. THIS 20TH CENTURY SURVEY PROVIDES STATISTICAL EVIDENCE ON THE RELATIONSHIPS BETWEEN KEY VARIABLES IN REVOLUTION SUCH AS RAW CHARACTERISTICS, DIRECTORATE, PERSONNEL, GOALS, FACILITIES, FOREIGN AID, AND INITIATIVES. FINALLY, THE INDIVIDUAL AND REVOLUTION IS EXAMINED. THIS STUDY DISCUSSES REVOLUTIONARY ACTIVITY IN GENERAL, THE REVOLUTION AND THE OUTSIDE WORLD, COMMUNICATING REVOLUTIONARY IDEAS, AND THE REVOLUTIONARY IN A COMPLEX SOCIETY. APPENDIXES PRESENT A CHECKLIST OF REVOLUTIONARY TRANSITIONS IN THE 20TH CENTURY, A CODE LIST OF VARIABLES FROM THE SURVEY, A BIBLIOGRAPHY, AND INDEX. (DAG)