THE FOLLOWING HYPOTHESES ARE DEVELOPED IN AN EXAMINATION OF THE EFFECTS OF INTERNAL POLITICAL STRUGGLE UPON TRADITIONAL COLOMBIAN MILITARY PROFESSIONALISM WHICH REMOVES THE MILITARY FROM POLITICS: (1) WHERE THERE IS CONSIDERABLE CONSENSUS AND LITTLE OR NO ARMED POLITICAL CONFLICT, ANY MILITARY PARTICIPATION IN POLITICS IS LARGELY INDEPENDENT OF THEIR PROFESSIONALISM; (2) WHERE POLITICAL CONSENSUS BREAKS DOWN TO THE POINT WHERE VIOLENT PARTISAN CONFLICT BECOMES ENDEMIC, THE ARMED FORCES, THOUGH LIKELY TO ASSERT 'PROFESSIONAL' NEUTRALITY, ARE INEVITABLY DRAWN INTO FAVORING ONE OR ANOTHER PARTY IN THE VIOLENT DISPUTE, USUALLY THE PARTY IN CONTROL OF THE STATE; AND (3) UNDER CONDITIONS OF INTERNAL WAR, THE TENSION BETWEEN MILITARY PROFESSIONALISM AND PARTISAN POLITICAL INVOLVEMENT TENDS TO BREAK DOWN, AND THE DISCIPLINE AND SKILLS INHERENT IN PROFESSIONALISM PROMOTE THE INVOLVEMENT OF THE ARMED FORCES IN POLITICAL AFFAIRS. THE ANALYSIS ALSO SEEKS ANSWERS TO TWO GENERAL QUESTIONS: HOW DOES THE NATURE OF THE INTERNAL ENEMY AFFECT THE MILITARY'S PARTISAN AND NONPARTISAN ROLES? IN WHAT WAYS DOES PROFESSIONALISM AFFECT THE MILITARY'S CONDUCT IN WAGING WAR AGAINST VIOLENT GROUPS IN ITS OWN SOCIETY? THESE PROBLEMS ARE ADDRESSED BY EXAMINING THE NATURE OF INSURGENCY IN COLOMBIA AND THE MISSIONS, STRATEGY, AND INSTITUTIONAL CHARACTERISTICS OF THE COLOMBIAN MILITARY UNDER THE IMPACT OF PROLONGED GUERRILLA WARFARE. TABULAR DATA, A BIBLIOGRAPHY, NOTES, AND AN INDEX ARE PROVIDED. (RCB)