This chapter discusses the major controllable variables in developing promotional messages: the source or communicator, the message structure and appeals, and the communication channel. It focuses on how decisions about these variables should consider their impact on consumers' response process. A persuasion matrix is presented to help marketers evaluate how each variable interacts with steps in a receiver's response. Key aspects of source credibility, attractiveness, and power are defined. Different types of message appeals and structures are examined. Finally, the chapter distinguishes between self-paced and externally-paced communication channels.