Two-Dimensional Groups, Orbifolds and Tilings Ludwig Balke and Daniel H. Huson Abstract: Given the triangulation of a 2-dimensional orbifold in terms of the Delaney--Dress symbol of a periodic tiling, we discuss how to compute it's orbifold symbol, as defined by J.~Conway. It is shown that the number of types of equivariant tilings depends only on the ``form'' of the corresponding orbifold symbols. The method is applied to obtain a refined classification of equivariant tilings for certain hyperbolic symmetry groups. Appeared in: Geometriae Dedicata, 60:89--106, 1996