By preschool age, children have a sophisticated assumption about the conventional nature of various kinds of information. The present studies investigated the role of two cues in 2-and 3-year-olds' determination of what is conventional, namely the intentionality and intra-individual consistency in the use of objects. Overall, in Study 1, both 2-and 3-year-olds were more likely to say that the expected use and purpose of an object was a function intentionally and consistently demonstrated. In Study 2, 3-year-olds but not 2-year-olds generalized their expectation about the conventionality of an intentionally demonstrated function to another agent's learning of the function. These findings shed light on how children's assumption of what is conventional gets refined via children's intuitive interpretive dispositions regarding human actions.