All animal behaviors depend on engaging the motor system. Yet, despite its central importance, we know very little about how the motor system is engaged by nervous systems to generate highly rhythmic locomotor behaviors, such as walking. Moreover, the same motor systems that are used for walking have the remarkable facility to be reconfigured in a wide variety of ways, for example, to allow animals to run, jump, or scratch an itch. Our long-term goal is to understand how animal nervous systems produce such distinct motor outputs using the same set of motor neurons and muscles, with a focus on locomotion. We study this problem in the fruit fly because of its powerful genetic tools and complex—but not too complex—set of behaviors and nervous system. In my talk, I will describe our efforts to develop high resolution assays to study locomotion in the fruit fly, our recent attempts to genetically dissect this neural circuitry, and how a common motor ground plan can be modified by neuromodulators to execute alternate types of related motor outputs. I may also describe our efforts to dissect the development of the motor system, since how it is constructed may provide important insights into how it functions.