Repeated but unadvised attempts have been made by music educators to relate the Piagetian concept of concrete operational thought to children's understanding of music. The attempts have been focused on the apparent link between the child's detection of invariance in musical patterns and the concept of conservation. These attempts are unadvised since it is generally impossible for the child to infer, as Piaget's theory requires, that musical properties remain invariant. Since processes of perception and memory are extremely important in the child's response to a musical passage that has been altered or distorted (i.e., transformed), a possibly more promising link between Piagetian concepts and the domain of music can be found in Piaget's analysis of children's response to temporally structured stimuli. The key concept to introduce in this connection is that of "expectancy". Expectancies are directly tied to Piaget's concept of schema, as investigated by Hunt and others, and to the development of the "concept of the match" between a stimulus and a preexisting schema. Children's emotional response to certain aspects of music, such as the violation of expectancies through alteration or distortion of a musical passage, appears to be understandable in terms of the growth of schemata through Piagetian processes of assimilation. More particularly, children's emotional responses can be understood in terms of the positive contribution of the experience of moderate discrepancies from schemata to children's cognitive growth. (The paper closes by drawing attention to the importance of the affective component in the response to music.) (Author/RH)