Controversy regarding the nature and frequency of knowledge transfer has received significant attention for more than a century, and this debate has sparked advances in our theoretical understanding of transfer as well as educational practices designed to promote it. We review the classical cognitive approach to studying transfer and highlight several important critiques of that approach regarding issues of context, assessment, and individual differences. These critiques have pushed research to improve understanding of the learning processes that facilitate transfer, the application processes that enact it, and the measurement of it. Research investigating the relationship between achievement goals and transfer serves as an example of the ways issues of context and individual differences are being integrated into the study of transfer. Future work on transfer should continue to refine and clarify how we define, assess, and promote it.