This paper applies the limited capacity model of motivated mediated messages (LC4MP) to the problem of creating effective messages about cancer. A general description of the model is presented and then applied specifically to the task of creating effective cancer communication messages by asking the following questions about cancer communication: (a) What is the goal of the message? (b) Who is in the target market? (c) What medium will carry the message? and (d) What is the motivational and personal relevance of the main information in the message for the majority of people in the target market? The paper concludes that cancer is a motivationally relevant topic that will elicit aversive activation. Target markets for various types of cancer-related messages (e.g., smokers or people of a certain age) will process mediated messages in predictably different ways making certain design decisions better for certain target markets. Both structural and content elements of messages interact with the limited capacity information processing system to impact resource allocation, which in turn determines how well messages are encoded, stored, and retrieved at a decision point. Individual differences in peoples’ motivational activation influence both their tendencies to engage in risky behaviors that increase the probabilities of getting cancer and their processing of health-related messages. Future research from this perspective should be done to optimize cancer messages for specific target audiences using specific media.