Uncertainty is a part of any IS project. When developing something new and previously untried there must be uncertainty. In the literature, however, uncertainty is often mixed with risk and treated solely through risk management. We decided to take a closer look at uncertainty. Based on in-depth analysis of qualitative interviews with experienced IS project managers we identify four different types of uncertainty, which we call Task uncertainty, Collaborative uncertainty, Process uncertainty, and Individual uncertainty. We also derive project management coping strategies for dealing with each of the four kinds of uncertainty.