This training study examined the effect of preschoolers' experience with conversational breakdown on their understanding of one aspect of the process of knowing, namely, that the quality of information that is being accessed matters for knowledge acquisition. Children between the ages of 3;1 and 5;0 years (mean age: 3;10 years) were pre- and post-tested on their ability to predict and justify a listener's state of knowledge about the contents of a box after the listener was provided with ambiguous and informative messages about the contents of the box. Between test sessions, children were assigned to one of three training conditions. In all conditions, children observed, from an onlooker perspective, while a speaker provided ambiguous and informative messages to a listener about the contents of a box. In a general-feedback condition, children were informed about whether or not the listener gained knowledge after each message. In a specific-feedback condition, children were informed about whether and why the listener gained knowledge after each ambiguous message, and whether the listener gained knowledge after each informative message. In a no-feedback or control condition, children were not informed about the listener's state of knowledge after each of the messages. Analyses of change of scores demonstrated that children in the general- and specific-feedback conditions improved from pre- to post-test on their ability to predict the effect of ambiguous and informative message on the listener's knowledge. Moreover, results showed that children in the specific-feedback condition made the greatest gains of training. Posttest comparisons demonstrated that they outperformed children in the general- and no-feedback condition on their ability to justify their predictions about the listener's state of knowledge after ambiguous and informative messages. No learning effects, however, were observed on any of the training conditions in a transfer task that evaluated children's understanding of the implications of access to ambiguous visual information on an observer's knowledge. Effects of children's experience with conversational breakdown for their communicative development and their understanding of the process of knowing are discussed.