The aim of the present research was to investigate the psychological processes driving outgroup helping intentions among ethnic groups actually involved in natural disasters. We proposed that disaster exposure would be associated with different degrees of outgroup helping intentions depending on victim’s ethnic group of belonging. Specifically, based on an integration between the common ingroup identity model (Gaertner & Dovidio, 2000) and the integrated threat theory (Stephan & Stephan, 2000), we hypothesized that perceived disaster exposure would be negatively associated with ethnic majorities’ altruistic intentions via increased outgroup threat, and it would be positively associated with ethnic minorities’ altruistic intentions via enhanced one-group perception. The findings of our research conducted with Italian natives (i.e., majority group) and immigrants (i.e., minority group) struck by the 2012 Northern Italian earthquakes fully supported our predictions. Implications of these findings for developing “altruistic” communities in postdisaster contexts are discussed together with the importance of considering the combined contribution of different psychological theories.