  We study the prescribed scalar curvature problem in a conformal class on
orbifolds with isolated singularities. We prove a compactness theorem in
dimension $4$, and an existence theorem which holds in dimensions $n \geq 4$.
This problem is more subtle than the manifold case since the positive mass
theorem does not hold for ALE metrics in general. We also determine the
$\rm{U}(2)$-invariant Leray-Schauder degree for a family of negative-mass
orbifolds found by LeBrun.
