The impact of shifting epistemologies in the field of instructional design during the last century has had a major impact on how we design instruction. The goal of this chapter is to provide an overview of important shifts in ideas about what knowledge is, how it can be produced or constructed, and what it has meant for instructional design in the last decade. We discuss how technology has influenced instructor, learner, and designer beliefs about knowledge, instruction, and learning. Furthermore, we look at the changing landscape of theory and research that supports and questions these perspectives, and the implications it has on instructional practices.