In this thesis I describe the use of behavior hierarchies based on ﲭerging two models of multi-layer architecture --- the supervenience model of [18] and the subsumption model of [6]. The behavior hierarchy approach allows us to use the robustness of reactivity in behavior design. It also encourages the design of modular behaviors that can be reused or more importantly recalibrated in different situations. I argue that behavior hierarchies extend our ability to design and program effective solutions that combine reactive and goal-driven components, but do not require any explicit planning. This work is used for an implemented system in which the underwater robot SCAMP developed at the Space Systems Laboratory at the University of Maryland performs vision-based behaviors to relieve a human operator of certain tasks.