The rise of ISIS and the recent terrorist attacks in Europe have raised a collective alertness for a potential terrorist attack. The presence of jihadist networks in the Netherlands, and the significant outflow of young people to conflict areas in the Middle East to join the jihad, have greatly enhanced this anxiety. But how are these networks organized, and how do they prepare their jihad? How do people get involved in jihadist networks, and how important is ideology in this regard? Answering such questions will help to understand how jihadist networks operate, which can be useful knowledge for policy makers and practitioners who aim to counter terrorist threats. Using unique data from police files, interviews and trial observations, while utilizing different analytical methods, this study provides an in-depth insight into the modus operandi of jihadist networks in the Netherlands. The findings show how jihadist networks have changed over the years and how this development has affected the way jihadist networks operate.