The primary concern in current interaction design is focused on how to help users solve problems and achieve goals more easily and efficiently. While users' sufficient knowledge acquisition of operating a product or system is considered important, their acquisition of problem-solving knowledge in the task domain has largely been disregarded. As a result, domain knowledge has not been appropriately incorporated into design processes, and users' learning of domain problem-solving methods tends to be detached from actual user experiences. Without sufficient domain knowledge, users will not be able to creatively adjust their product/system use in order to achieve satisfactory results and generate better experiences. This research aims to develop a methodology for designing interactive products/systems that can help users actively develop their problem-solving abilities through interaction. This new approach, named the Learning-Based Approach (LBA), is framed by theoretical and empirical investigations of users' knowledge development during product use. Based on theoretical reviews, the present research proposes some models of users' learning processes, which describe motivational factors, cognitive processes, and contextual influences on learning. This research also suggests some design principles for enhancing users' learning in interaction, based on theories and user study results. In these models and principles, users' domain knowledge development is posited as a key factor for improving current user-product interaction. In order to help designers effectively incorporate domain knowledge into design processes, this research proposes some LBA methods that consist of several phases: 1) understanding domain knowledge (DK) structure; 2) analyzing users' operational tasks; 3) mapping between DK and tasks; 4) delivering DK via user interfaces; and 5) developing prototype specifications. A computerized design-supporting tool is developed for helping designers apply the methods to their design practices: this tool is named the Domain Knowledge-based Design Tool (DKT). The LBA methods are demonstrated by developing a digital camera prototype, and are evaluated by conducting user tests with the prototype. The test results show that the LBA-applied design positively affected users' motivation for learning and their domain knowledge development. This dissertation concludes by identifying some research contributions and limitations, and some directions for the future development of the research. [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.]