Today, the Colombian humanitarian crisis of internally displaced persons (IDPs) is one of the mainfactors contributing to the growing number of people who rapidly become extremely poor, and floodinto “belts of misery" in, and around, major cities. This paper examines the impact of the internal armed conflict in contemporary Colombia on the well-being of IDPs, through analysis of causal connections between the internal armed conflict, internal displacement and the process of impoverishment of IDPs.In this research paper we provide a historical overview of the development of the internal displacement phenomenon in Colombia and evaluate changes in various socio-demographic characteristics of IDPs due to the internal displacement during the 1990s. In order to demonstrate the way in which thearmed conflict in Colombia has contributed to the worsening of living conditions of a significant part ofthe Colombian population, we draw upon statistics that demonstrate who bears the responsibility forforcing people to migrate to the cities, and to figures showing the loss of assets by IDPs. Finally, byanalysing the key facets of Plan Colombia, a major initiative, with the participation of the United States,to combat the illegal drug industry in the Western hemisphere, introduced at the end of the 1990s, weconclude that the issues of international cooperation, armed conflict and internal displacement in Colombia are very closely interconnected, and that they are of great importance, not only for IDPs themselves, but also for the whole of Colombian society and for the country's future development.