Chemotactic bacteria navigate their habitats by monitoring and responding to environmental chemical gradients. For numerous human and plant pathogens, this behavior is essential for effective colonization and infection. The chemotaxis process requires large, highly-ordered transmembrane protein complexes known as chemosensory arrays. Functioning as a kind of bacterial brain, chemosensory arrays convert the binding of chemical ligands (sensory input) into changes in cell swimming pattern (motile output) using a universally-conserved architecture. In this talk, I will discuss recent work combining cryo-electron tomography with molecular modeling and simulation to produce the first, high-resolution structural characterization of a complete bacterial chemosensory array, namely that of the model organism E. coli. I will also relate ongoing computational efforts to describe the residue-level details of critical sensory signal transduction mechanisms within the array. These results, combined with genetic and biochemical approaches, provide a much-needed molecular basis for the design of new experiments and the development of a comprehensive model of bacterial chemosensing.