With rapid advancements in information and communication technologies, computer-mediated communication channels such as email, web, mobile smart-phones with SMS, social networking websites (Facebook), multimedia websites, and OEM devices provide users with multiple technology choices to seek information. However, no study has compared the effectiveness of any of the above channels to persuade users through certain persuasive strategies to change their behavior. We explore strategies such as praise, reminders, suggestions, and rewards applied in the context of health behavior and promotion. Does effectiveness of the persuasive technology system vary by the communication channel and strategies used? If so, which kind of communication channel provides the most persuasive impact for a specific persuasive strategy? Moreover, how affective computing (adding emotional content such as indicators for happiness, sadness, empathy etc.) impacts the effectiveness of persuasive systems has remained unexplored. This study tests three hypotheses (1) that computer-mediated communication channels in combination with persuasive strategies have different persuasive effectiveness; (2) that adding emotion to a message that leads to a better overall user experience by enhancing pragmatic and hedonic aspects, which can increase persuasive effectiveness; (3) that there is a positive correlation between the amount of information, as measured by entropy, carried by a persuasive message and its persuasive effectiveness. This study uses both design science research (DSR) and quantitative research methodology. First, a simulation system is designed and built to represent the persuasive systems with various combinations of communication channels and persuasive strategies using mock-up technology. The design of the mock-ups follows DSR methodology to guide the development of the simulation system. The affective computing feature is added to the experiment using emoticons. Then, this simulation system is used in an experimental design to quantitatively measure persuasive effectiveness and user experience under those combinations. In addition, this study investigates the entropy of the persuasive message. The results of the study show that computer-mediated communication channels in combination with various persuasive strategies can affect the persuasive effectiveness to differing degrees. These results also show that adding an emoticon to a message leads to a better user experience, which increases the overall persuasive effectiveness of a system. Based on these results, the study delineates a model to predict persuasive effectiveness based on user experiences. Our findings can benefit online advertising companies, health promotion agencies as well as designers of persuasive technologies to select channels, strategies and affect to meet their needs with target audiences. Finally, the study demonstrates that the image entropy of the whole graphic interface of the system is a better entropy measurement than text entropy, and it has a positive relationship to the system's persuasive effectiveness. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]