Many economic decisions rely on information that is privately owned by the agents, who may have incentives to misreport this information. The strategic possibilities of the agents may take different forms, depending on the economic environment. The first chapter studies the scheduling problem, and considers coalitional maneuvers in the form of splitting and transferring jobs. The second chapter explores strategic behavior in the form of merging by users in the minimum cost spanning tree problem. The third chapter is about decision making under uncertainty, where we give an alternative characterization of individual preferences that are based on beliefs.