The paper develops a theory of costly communication in which the sender's and receiver's motivations and abilities endogenously determine the communication mode and the transfer of knowledge. Communication is modeled as a problem of moral hazard in teams, in which the sender and receiver select persuasion and message elaboration efforts. The model is shown to provide a rich set of insights concerning (i) the impact of incentive alignment on communication strategies, (ii) the relative influence and the complementarity/substitutability between issue-relevant communication and cues (information that relates to the credibility of the sender rather than to the issue at stake), and (iii) the path dependency of communication. (Contains 27 notes.)