Economics tries to give an answer to the question of how unlimited wants are to be satisfied with a only limited supply of resources. Th aim of this dissertation is to continue the work of finding new areas in which the theory of mechanism can be employed to yield better outcomes than are possible with currently practiced approaches. The range of applications that is considered highlights the general applicability of the basic principles of mechanism. However the particular form that mechanisms take will depend on the precise situation. While the four papers that together comprise this thesis consider different applications, they are linked by their use of the theory of mechanism design and information economics. The dissertation is split into two parts. The two parts, Mechanism Design and Market Design, are distinguished mainly by the preferences that are assumed for the agents. In Mechanism Design the focus lies on models in which agents are assumed to have cardinal preferences. In Market Design models in which agents have ordinal preferences are considered. The first two chapters on merger policy and congestion pricing can be seen as pertaining to the literature on mechanism design. In the first chapter the role of asymmetries of information in merger policy is considered, while the second chapter shows how the problem of congestion can be treated as a mechanism design problem. The third and fourth chapter are within the field of market design. The third chapter considers the problem of allocating lawyers to courts for their mandatory traineeships and proposes a new method of doing so. The fourth chapter revisits the question of strategic schools under a frequently used algorithm to allocate students to schools.