non-abelian $c^\ast$-algebras can be understood better from the examination of their maximal abelian subalgebras. in particular, renault showed that in the presence of a cartan subalgebra, a $c^\ast$-algebra can be associated in a canonical way with a topological twisted groupoid. in joint work with jon brown, adam fuller, and david pitts, we extend renault's result by identifying cartan pairs revealed by gradings by a group.