Shadow Models is an incremental transformation framework for MPS. The name is motivated by the realization that many analyses are easier to do on an AST whose structure is different from what the user edits. To be able to run such analyses interactively in an IDE, these ``shadows'' of the user-facing AST must be maintained in realtime, and incrementality can deliver the needed short response times. Shadow Models is an incremental model transformation engine for MPS. In the paper we motivate the system through example use cases, and outline the transformation framework.