This paper focuses on the role of communication, in particular of social media, during all the phases of an emergency. Through the use of these new ways of disseminating information, procedures and actors involved in the emergency communication process have sensibly changed: people are no more only information consumers, rather they are gradually becoming producers. Thus, to what extent can engaging the public through social media be effective within the broader management cycle? In order to answer this question, the paper analyzes an Italian case study about the use of Twitter during the cyclone in Sardinia and discusses derivated responsibilities for both Institutions and the public should a communicative engagement process be adopeted.