Statelessness is a legal concept describing the lack of any nationality. The citizenship is primarily a source of rights, or in other words, the "right to have rights". The article describes and analyzes activities of international organizations to reduce statelessness. In this context, issues such as the scale of the problem of statelessness, its causes, conditions and consequences are going to be discussed. This approach allows us to demonstrate the relationships between the problem of statelessness with the other issues analyzed in the book, such as migration and refugee problems. Both institutional and operational activities of selected international organizations regarding statelessness will be examined. Considerations devoted to the activity of selected international organizations will begin with drawing attention to their contribution to the codification of international law. Only organizations that have the greatest achievements in the subject are going to be described. Among them: the United Nations (United Nations, UN), European Union (European Union, EU), the Organization for Security and Cooperation in Europe (Organization of Security and Cooperation in Europe, OSCE), the Council of Europe (Council of Europe, RE) The AU (African Union, AU), Association of Southeast Asian Nations – Eastern Europe (Association of Southeast Asian Nations, ASEAN).