The “Arab Spring” in Syria has swiftly turned into a multilayered and total war involving – in a variety of ways – global, regional and local actors, some in an official (inter-)governmental capacity but many in other capacities obeying to logics that challenge common understandings of border and identity, time and place. This paper aims at studying one such instance: the involvement of Lebanese non-state actors in Syria. Considering the extent of their respective involvement in the Syrian conflict in spite of the Lebanese governmental “policy of dissociation”, two non-state actors have been selected: Hezbollah that supports the Syrian regime, and informal Sunni movements that have embraced the fight of jihadi groups. Beyond the assessment of who these actors are and how they involve in the conflict, the research devotes special attention to what our exploratory fieldwork shows to be a key mobilizing factor: the reconstruction of identities across the borders. Accordingly, the paper will answer notably questions about how some places have been given special meanings, prompting Lebanese youngsters to fight and die in Syria; how identities have been reframed to mobilize across borders; and beyond, how and why such identity mobilizations have been that successful. Based on more than 35 interviews already conducted in Lebanon with a variety of actors and observers, our research shows differentiated patterns of identity mobilization: whereas Hezbollah’s operatives are bound to a powerful top-down organization with an agenda underpinned by both geo-strategic calculations and identity politics, the involvement of Sunnis is rather made on an individual basis within networks of jihadists built almost exclusively on the activation of religious identities and enmities. While “assabiya” proved to be paramount in the first group, social anomy has been found essential in the second one. Interestingly, the research has shown that both these phenomena that make identity so prone to activation that people opt for a path leading to a likely if not a certain death, are bred by two key factors: the failure of the Lebanese state and society to build a meaningful political project for the youth, and the failure of both regional and international actors to sooth rather than instrumentalize differences in the region. Both these failures have led to polarization and ensuing narratives of victimization and hence sustained the cultivation of transnational primary identities at the expenses of national belonging.