Design is an inherently interdisciplinary enterprise and the design of learning technologies is no exception. Learning technology designers must consider issues from a range of disciplines, such as software design and human-computer interaction (HCI), learning sciences, and related content domains. But while designers and researchers can draw from existing work in these different disciplines, there are still many questions to explore about the design, use, and impact of learning technologies. From a learning sciences perspective, there is much to learn about how learners work with technologies in different contexts and what the ultimate impacts of those technologies are, especially as we consider new media and communication functionalities. From an HCI perspective, there is much to learn about specific design methods and frameworks that go beyond the typical HCI focus on usability to focus on developing and assessing learning technologies. The development process thus leads to a disciplinary interplay: oour understanding of learners and learning leads to certain design approaches, which leads to learning technologies that we can assess to gain knowledge about learners and learning, which can lead to refined design approaches and the cycle continues to build our knowledge of HCI and learning.