Methods and systems for preserving unknown markup in a strongly typed environment are described. In but one embodiment, XML-based markup that may contain XML-based elements that are both known and unknown is received. A strongly typed tree that is associated with the known XML-based elements is instantiated and a weakly typed tree that is associated with both the XML-based known and unknown elements is instantiated. The strongly and the weakly typed trees are then correlated in a manner that preserves the unknown XML-based elements.