Adaptive behavioral capabilities are necessary for robust navigation in non-engineered environments. A control approach to adaptive behavior is described which exploits the approximate reasoning facility of fuzzy logic. In particular, a behavior-based architecture for hierarchical fuzzy control of mobile robots is presented. Its structure is described as well as mechanisms of control decision-making which give rise to adaptive behavior. Control decisions result from a consensus of recommendations offered only by behaviors that are applicable to current situations. Indoor navigation examples demonstrate the practicality of the approach and reveals characteristics of multiple behavior interaction.