Résumé : Until recently, immigration policy was an issue solely reserved to national governments, but nowadays more and more cities and municipalities around the globe are expressing concerns and getting involved on the matter. While there’s an expanding body of literature in the Welcoming Cities subject, questions remain about the factors involved in the local policy makers’ decisions to do local immigration policy. This research then analyzes how one specific actor, large scale pro-immigration networks, influences local immigration policy decisions via a case of study: The Commune Hospitalière movement in the Brussels-Wallonia region of Belgium. By examining a diversity of written empirical information, this research has traced the strategies and mechanisms of influence used by the movement to influence local policy makers. Two main findings are exposed. The first one, that this kind of actor provides resources and expert guidance both to local activists and politicians involved in the policy process, facilitating then their involvement in the process and influence their decision on the adoption of welcoming motions. The second one, that large scale pro-immigrant networks are successful in keeping the subject of local immigration policy in the general political agenda of the region, by constantly sharing information and creation pressure around the subject. The aim of this research is to show an in depth view of how local immigration policy process are occurring, and how this process are actually making a difference for migrants and their communities.