Observation of 8 mother cats and their litters revealed that the previous occurrence of a kitten vocalization was associated with an increased probability that mothers would approach kittens, change to a different body position, shift their lactation position, or vocalize. When the effects of kitten vocalizations were separated from other kitten-emitted cues, the vocalizations reliably elicited approach and investigation of the sound source from mothers. Mothers exposed to kitten vocalizations removed kittens from a box and carried them to the home site. Repeated testing of mothers demonstrated that these effects of kitten vocalizations on maternal behavior remained strong for at least the first 30 days of life. Vocalizations are a stimulus by which kittens influence their mother''s behavior.