This report describes the way in which jihadi terrorism manifested itself in the Netherlands at the outset of the 21st century, and focuses specifically on a few jihadi cooperations that were active on Dutch territory in the period between 2001 and 2005.What kind of groups were they? How were these groups formed? How were they organised? Which people were active in these groups? What was their aim? Which activities did they carry out? How did they operate? Researchers in the area of terrorism and counterterrorism have been engaged in these questions for years, but empirical research into this phenomenon is scarce. On the basis of information from closed criminal investigations, this report describes how these jihadi cooperations operated. It consequently provides a unique view of the world of jihadism, and makes a valuable contribution to the development of ourempirical knowledge in this area.This report is an integral translation of the report Jihadistisch terrorisme in Nederland which was published in the WODCseries Onderzoek en beleid (no. 281) in 2009.