A developmental analysis of ingestive behavior is proposed. The expression and control of individual components in the ingestive sequence will be studied in young rats. Particular emphasis will be placed on the investigation of the decrementing property of the oral response component which will be tested for its generality, duration, and potency. This intrinsic, habituation-like mechanism could be a principle integrator of ingestion-related signals. An integrative function for oral habituation would be indicated by influences of physiological state and postingestive signals on habituation parameters such as the initial level of responsiveness, rate of decrement, or duration of decrement. The relation of the oral component to other earlier components in the sequence will be assessed in experiments measuring olfactory orienting, and the potential brainstem representation of the oral habituation process will be evaluated in decerebrate pups. The proposed experiments offer a unique conceptual strategy and should provide instructive data on the neurobehavioral organization of a most fundamental appetitive behavior.