Behavior-based systems are one of the most popular paradigms for building controllers. Although this paradigm is intrinsically tied to the notion of modular design, most existing behavior-based controllers do not fully satisfy the important desiderata of modularity, hierarchical structure, and reconfigurability. In this paper we discuss these desiderata, and we describe a fuzzy controller that satisfies them. To illustrate the functioning of our controller, we show experiments run on both a simulator and a real robot.