The extent and type of weaponry currently available to terrorists, insurgents, and other criminals are enormous. These groups have exploited and developed local, regional, and global supply channels to traffic in munitions and equipment worldwide. In the country of Columbia, the drug trade, a protracted insurgent conflict, nationwide corruption, and small arms proliferation have contributed to the political instability and violence in the country over the past century with small arms proliferation among the most serious of the problems. This report analyzes the issue of small arms trafficking in Columbia which poses enormous challenges due to the difficulty in monitoring and measuring the movement of these weapons and which does not conform to traditional definitions of a security threat. “Small arms” is defined as man-portable personal and military weapons, ranging from handguns to assault rifles to surface-to-air missiles (SAM's). For this report, the analysis of small arms activity in Columbia is broken down into three distinct categories: (1) weapons users; (2) external sources and transportation routes; and (3) patterns of arms trafficking internally. The proliferation of small arms in Columbia is directly relevant to the United States for two reasons which are discussed. First the Fuerzas Armadas Revolucionarias de Colombia (FARC) is one of the largest and most well-funded militant organizations in the world. With the advent of the war on terrorism, FARC could focus more attention on United States targets. FARC has the resources and ability to strategically manage its weapons supplies and pose a threat to the United States. Second, small arms transfers have had a negative impact on regional stability in Latin America. Ready access to weapons by guerrilla and paramilitary forces threatens the security of the fourth-largest economy in Latin America. The report has five major sections: violence in Columbia; patterns of small arms trafficking into Columbia; patterns of small arms trafficking inside Columbia; the wider context; and policy implications. Appendix and references