In this chapter, I argue that instructional designers must use research and theory to guide them to new and justified instructional practices when designing e-learning. I introduce a well-established pedagogy, problem-based learning (PBL), in which complex, ill-structured problems serve as the context and stimulus for learning, and students work collaboratively to understand the problem and learn about the broader related concepts. I describe the structure of PBL and discuss Barrow’s (1998) concept of “authentic” PBL. I then review the support for PBL in the research literature and describe its relationship to cognitive and constructivist learning theory. I conclude the chapter by demonstrating how authentic PBL can be applied to e-learning using supporting examples from an undergraduate online course in agriculture.