It's generally agreed that testimony can be a source of knowledge and justified belief. The epistemology of testimony concerns itself with explaining how this can be the case. This thesis begins by identifying three types of explanation. According to the first explanation, my testimony can induce a justified belief in you because you use the reasons that you have available to you to infer the truth of what I say from the fact that I said it. According to the second explanation, my testimony can induce a justified belief in you because the processes involved in you forming the belief on the basis of my testimony are suitably reliable. And according to the third explanation, my testimony can induce a justified belief in you because I have justification for what I say and my testimony allows you to form a belief that's supported by this justification. Having identified three different types of explanation, I argue that neither the first nor the second type of explanation can give a full account of testimony as a source of justified belief. The idea is that a notion of justification transmission is indispensable to a complete epistemology of testimony. I begin by establishing what justification transmission amounts to (and what it doesn't amount to) and defend the idea from its various critics. Next I turn to consider the first explanation and offer an example that illustrates why it can't give a complete account of justification from testimony by itself. Lastly, I discuss the third explanation and argue that it too fails to provide a satisfying framework for understanding how testimony is a source of justified belief.