Function has been considered important in numerous literatures in the study of cognitive development, yet little is known about what and how infants learn about function. Five experiments examined what 10-month-old infants (N=80) learn about functions that involve a sound produced when an object is acted on. Infants habituated to a single object (Experiment 1) or multiple objects that performed the same function (Experiment 2) learned both the actions and the sounds. Infants did not appear to learn relations between actions and sounds (Experiment 3) or appearances and sounds (Experiment 4), although they did learn the relations between appearances and actions (Experiment 5). These results are discussed in terms of how infants learn about object function.