We study games of incomplete information as both the information structure and the extensive form vary. An analyst may know the payoff‐relevant data but not the players' private information, nor the extensive form that governs their play. Alternatively, a designer may be able to build a mechanism from these ingredients. We characterize all outcomes that can arise in an equilibrium of some extensive form with some information structure. We show how to specialize our main concept to capture the additional restrictions implied by extensive‐form refinements.

We study information as an incentive device in a dynamic moral hazard framework. An agent works on a task of uncertain difficulty, modeled as the duration of required effort. The principal knows the task difficulty and provides information over time. The optimal mechanism features moving goalposts: an initial disclosure makes the agent sufficiently optimistic that the task is easy. If the task is indeed difficult, the agent is told this only after working long enough to put the difficult task within reach. The agent then completes the difficult task even though he never would have chosen to at the outset.