In this paper we look at interactive architecture from a design theoretical/methodological point of view. In particular, we aim to outline how principles from agent theory can form a theoretical foundation for conception and following the design of interactive architecture. Interactive architecture is a special case of responsive buildings – buildings that can intelligently react to, or even anticipate, change. Interactive buildings have an internal representation of the user on which basis they reach decisions for the manipulation of the outside world. For the design of responsive and interactive buildings it is necessary to take change into account throughout the whole design process. This requires rethinking our notions about architecture and design processes. We define an agent, and show how it matches for objects, with increasing degrees of responsiveness. Agents by themselves are not enough to design interactive buildings – they also need to have a behavior defined. For this purpose we define attitudes as mode of operation for agents.