Experiments using a new dye-sensitized photoinactivation technique were employed to remove single identified cells in order to study the mechanism of central pattern generation in the lobster stomatogastric ganglion. The stomatogastric ganglion, containing only 30 neurons, produces two cyclic patterns, the pyloric and the gastric when completely deafferented. Both patterns were found to utilize a combination of cellular properties, synaptic properties and network interactions to generate their respective rhythms. Reciprocal inhibition, synaptically activated bursting and an endogenously bursting cell were responsible for generating the pyloric rhythm. We suggest a hypothesis, based on a simplified gastric circuit, to explain the generation of the gastric rhythm. We tested the hypothesis experimentally using the cell inactivation technique and showed that many of the predictions which derive from the model could be validated.