During development spinal networks generate recurring episodes of rhythmic bursting that can be recorded from motoneurons and interneurons. Optical imaging has identified a set of propriospinal interneurons that may be important in the production of this activity. These neurons are rhythmically active, are recurrently interconnected and have powerful projections to motoneurons. The excitability of this propriospinal network is depressed by activity and recovers in the interval between episodes. These and other observations have been formulated into a qualitative model in which population behavior and self-organization are responsible for the spontaneous activity generated by developing spinal networks.