In contrast to calculable risks, uncertainty-understood here as the unexpected and non-calculable-is under-researched despite its societal and organizational relevance and omnipresence. Against this backdrop, the present study investigates how organizations practise uncertainty in the face of the numerous large-scale outbreaks of disease in Germany between 2000 and 2012. I position this study in the body of knowledge on disasters and crises, normal accident theory, and high-reliability organizations, and propose a practising uncertainty perspective that focuses on how to deal with unexpected external events and/or their latent dangers. I identify two overarching forms of practice, namely, reducing (i.e., coping with unforeseen incidents) and inducing (i.e., championing an overarching cause) uncertainty. I show that actors use both these forms of practice, which constitute the basis of the framework introduced herein, intentionally or unintentionally depending on the differing and sometimes conflicting objectives of the organizations involved.