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.