Newly hatched ducklings were exposed to imprinting procedures and their subsequent filial reactions were studied using a classical conditioning paradigm. The first experiment revealed that a previously neutral stimulus can become a conditioned suppressor of distress calling as a consequence of pairing it with the imprinted stimulus. If the presentation of the imprinted stimulus was, however, omitted or delayed, or if it preceded rather than followed the presentation of the neutral stimulus, the effect was not obtained. The second experiment utilized a differential conditioning procedure to investigate the capacity of imprinted ducklings to come under discriminative control. Two differently colored lights were used as stimuli; one was consistently followed by presentation of the imprinted stimulus, the other was never followed by its presentation. Only the former stimulus came to suppress distress calling. The importance of the apparent interaction between classical conditioning and imprinting is noted.