Background. The COVID-19 pandemic characterises a tremendous form of a global crisis resulting in public distress; hence, it is vital to gain a better understanding of citizens’ crisis concerns to increase public resilience.

Purpose. To provide implications for future crises, the purpose of this research is to explore what kind of social discourse drives citizen engagement on social media platforms to better understand their needs during a crisis. This is structured according to the three engagement expressions: topic, emotional and behavioural forms of social discourse.

Method. We follow a constructivist grounded theory methodology and, using convenience and theoretical sampling, we examine 334.036 textual and behavioural data points scraped from social media. By use of topic and sentiment mining with an additional behavioural engagement analysis we have an abductive research approach.

Results. The results show that 19 topics can be identified which impact citizens’ life immediately or mediately. Immediate effects are caused by the pandemic while mediate effects contain social discourse discussed independent of the crisis.

Discussion. We extent current literature due to our approach of incorporating citizens’ perspective on researching citizens’ crisis needs on social media. Moreover, we develop constructivist grounded theory on how online two-way communication behaviour between citizens can drive citizen engagement during a crisis.

Future research. By using our explorative research, we recommend future researchers to test different factors that drive citizen engagement on social media during a crisis using citizens’ perspectives.