In this contribution we investigate the online space of pro-migration mobilization in Belgium. First we identify actors of the mobilization on Facebook then leverage their discursive practices to uncover cognitive and structural patterns and map them upon a multi-dimensional space of mobilization.In reaction to the refugee reception crisis of 2015, citizen movements sprouted up over Europe in solidarity with the struggles of the migrants. These new movements worked alongside traditional actors such as trade unions, associations, and universities. However, in Belgium, citizen activist discourses and actions reproduced, and even reinforced, the institutional distinction between 'asylum seekers' and 'economic' migrants.How do these new actors blend into the Belgian activist scene? And how have traditional actors dealt with divergent philosophies and mobilisation repertoires? The present contribution addresses the reconfiguration of the French-speaking Belgian activist scene by analysing a network of 116 Facebook pages, which support migrants, and their publications between 2014 and 2018 (38 000 posts, 2.4 million words).Conducting an analysis of such an amount of data requires a multidisciplinary approach which efficiently combines both quantitative and qualitative methods. For this purpose, our methodology relies on three levels of analysis of varying granularity: a network analysis, a computational linguistics model, and a discourse analysis. First, we construct a network made of publications shared between pages to identify community structure and actors' prominence. Second, by means of a probabilistic topic model, we analyse the whole corpus and its thematic trends to extract discursive similarity between actors and its evolution over time. Third, we rely on discourse analysis to focus on nouns used to designate human groups (such as "movement") and their members (such as "refugees"). This approach emphasises the way actors express relationships and their network in terms of belonging, identity, and affiliation ...