Can we gain understanding from speakers who themselves fail to understand? At first glance, this looks counter-intuitive. How could a hearer with a poor understanding of a certain subject matter, or none at all, non–accidentally extract information relevant to understanding from a speaker’s testimony if the speaker does not understand what she is talking about? In this chapter I show that, when there are theories or representational systems working as epistemic mediators, speakers can intentionally generate understanding in their hearers by engaging in relevant speech acts without understanding the topic of these speech acts themselves. More specifically, I argue that testifiers can intentionally elicit understanding ofphenomena in their hearers even if they themselves lack such understanding—provided that they properly understand the epistemic mediators involved.