Graduation date: 2007Floods are the most frequent and damaging of all types of natural disasters and annually affect the lives of millions all over the globe. However, researchers seem to have overlooked the fact that floods do not recognize national boundaries. Therefore, the phenomena of shared, or transboundary floods occurring in international river basins (IRBs) is rarely touched upon. Consequently, vulnerability to shared floods is poorly understood and not much is known about the present quantity and quality of institutional capacity to deal with such events. Hence the primary purpose of the present work is to fill this gap in knowledge. We explore transboundary river flood events and related institutional capacity in more detail, starting at a global scale, zooming in on international river basins (IRBs) and ending with a country-scale perspective. The first section assesses how many of all floods were riverine and how much of these were shared between two or more countries. The results show that transboundary floods are more severe in their magnitude, affect larger areas, result in higher death tolls, and cause more financial damage than non-shared river floods do. The second section reveals an alarmingly low institutional capacity related to transboundary river floods: more than 15% of the IRBs do not have any type of institutional capacity in the form of a river basin institution, nor any focused on floods. The third section examines flood events, international water treaties signed and institutions created in the Netherlands and Mozambique. The comparison indicates that lower levels of development or the absence of development capital do not necessarily have to result in future (shared) flood-related disasters. Collectively, these results significantly increase our current knowledge on vulnerability to –transboundary– river floods and indicate that there might be more need for official international institutions dealing with these events. However, selecting the one country, continent or IRB that is the most vulnerable to –transboundary– river floods is impossible since the answer greatly depends upon the specific definition of vulnerability. This indicates that vulnerability to floods is a complex phenomenon that cannot be explained by using the results of only this study.