Achieving a successful Interactive Drama where the user can act as a character in the story requires not only finding an algorithmic solution for combining interactivity and narrativity, but also interfacing those algorithms with the user. This paper focuses on the way in which the user can choose the actions of the character. Three specific issues are discussed: the variety of choices proposed to the user, the need for the user to anticipate his/her future possibilities for actions and the time necessary to enter the action. This allows us to propose a taxonomy of different user interfaces and to evaluate the advantages and drawbacks of each category of interface. This should serve as a guideline for the design of user interfaces for Interactive Drama.