Given the widely accepted role of working memory (WM) in human cognition across tasks and domains, a central question has been, Is WM domain general? However, the term “domain-general” has been used in different, and sometimes misleading, ways. By reviewing recent evidence and biologically plausible models of WM, we show that the level of domain-generality varies substantially between three facets of WM: in terms of principles of processing, WM is largely domain-general. In terms of neural correlates, it contains both domain-general and domain-specific elements. Finally, in terms of application, it is mostly domain-specific. This variance encourages a focus shift towards uncovering domain-general principles and away from domain-general approaches to WM training, favoring newer perspectives, such as training-as-skill-learning, for the latter.