There is increased interest in the connectivity of migrants with both their host-lands and their original homelands. This article brings a social movement perspective to bear on the issue of diaspora mobilization. Why do conflict-generated diasporas from the same original homeland and living in the same host-land mobilize in sustained versus episodic ways? This article focuses on the sustained mobilization of Bosnian Muslims versus the episodic mobilization of Croats and Serbs in the Netherlands in the early 2010s. I argue that a traumatic issue that binds three actors – diaspora, host-state, and home-state – is central to such mobilization. This issue is the failure of Dutch peace-keeping forces to protect the Srebrenica enclave in 1995. Migration integration regimes, threats from radical right parties, host-state foreign policy, and transnational influences can trigger episodic diaspora mobilization, but not sustain it.