  Elmendorf's Theorem states that the category of continuous actions of a
topological group is a Grothendieck topos in the sense that it is equivalent to
a category of sheaves on a site. This paper offers a 2-dimensional
generalization by showing that a certain 2-category of continuous actions of a
topological 2-group is 2-equivalent to a 2-category of 2-sheaves on a suitable
2-site.
