In this chapter we address three types of uncertainty and how they affect three types of multiparty negotiations. In intra-team negotiations, multilateral negotiations, and negotiations that take place in marketplaces, negotiators need to recognize and manage uncertainty about the identity of negotiators, their interests, and who will be included in the final deal. In intra-team contexts, who is on team, the alignment of interests among team members, and how the final deal affects individuals on the team as well as the team itself may all be uncertain. In multilateral contexts, how an individual negotiator identifies the other parties, assesses the various interests of the various parties, and manages the coalitions that may form, all involve uncertainty. In marketplace contexts, the number and identity of competing negotiators, the idiosyncratic values that lead parties to be willing to bid different amounts, and the problem of matching with desirable counterparties create uncertainty. We discuss these various types of uncertainty in terms of the threats they present but also the opportunities that can be gained by negotiators who carefully manage them.