In this review of multiple reinterpretations of TPCK/TPACK that have emerged over time, we trace the construct’s roots not only to PCK, but more importantly to Shulman’s (1987) knowledge base for teaching, within which PCK was originally situated. We suggest that TPACK is a special case of PCK that sits within the considerably broader knowledge base for teaching, basing this assertion upon Cox’s (2008) explanation of the differences between teachers’ PCK and TPACK. Following Cox, we argue that TPACK references only the specific nature of a teacher’s PCK when unfamiliar digital tools are considered and implemented for educational purposes. We recommend that TPACK researchers distinguish among the different categories of teachers’ knowledge, reasoning, and action more clearly, bounding TPACK more narrowly in ways that mirror how Shulman delineated PCK with reference to the six other components comprising his knowledge base for teaching.