Abstract-A major challenge in deploying robots into the real world is the design of an architectural framework which can provide extended, natural and effective interactions with people. Within this framework, key issues that need to be solved relate to the robots' ability to engage in interactions in a natural way, to deal with multiple users, and to be continually perceptive of their surroundings. In this paper we propose a robot control architecture that addresses these issues. Our architecture has three main key features. First, it enables the representation of complex, sequential and hierarchical robot tasks, typically needed for service applications, in a behavior-based framework. Second, it provides the robot with flexibility in dealing with multiple users, such as to accommodate multiple user requests and task interruptions, over extended periods. Third, through its visual detection mechanism, the architecture allows the robot to identify when people are requesting its interaction. We demonstrate our approach on a Pioneer 3DX mobile robot, performing service tasks in a real-world environment.Index Terms-Human-robot interaction, behavioral robotics, personal robots.