It has been well over a century since the responses of bacteria to chemical stimuli were first documented by Engelman (1) and Pfeffer (2). In the 1960s, Adler reinitiated the study of bacterial chemotaxis (3), and during the past few decades, numerous laboratories have investigated the molecular basis of stimulus-response coupling in this system. The ability to study behavior in a unicellular organism with facile genetics has made bacterial chemotaxis an attractive model system for a diverse group of researchers, including geneticists, biochemists, biophysicists, and molecular, structural, and theoretical biologists. The biochemistry of the signaling pathway has been elucidated, and atomic resolution structures are available for most components of the signaling circuitry. This raises the possibility of eventually achieving a complete understanding of the mechanisms through which protein modifications and protein–protein interactions control the flow of information in this model sensory system. However, with the opportunity to pursue investigations at an ever-increasing level of molecular detail, there is a tendency to lose sight of the bigger picture. There is still a lot to be learned from the swimming responses of bacterial cells. In fact, it is the behavioral responses that molecular investigations seek to explain.