Matthijs Gardenier is Doctor in Sociology. His research is on social movements, political violence and social media. He completed a PhD on the sociology of crowds and on crowd policing at the University of Montpellier. Since then, he has been working on anti-migrant movements and on conservative participation to security and policing, with a focus on vigilantism. From 2019 to 2021, he conducted a British Academy Newton International Fellowship at the University of Manchester on anti-migrant groups in Dover and in Calais. Matthijs Gardenier has also been teaching at the Universities of Montpellier and of Brasilia (Brazil) since 2012. He has also produced several sociological documentaries.