2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/98182We classify those curvature-homogeneous Einstein four-manifolds, of all metric signatures, which have a complex-diagonalizable curvature operator. They all turn out to be locally homogeneous. More precisely, any such manifold must be either locally symmetric or locally isometric to a suitable Lie group with a left-invariant metric. To show this we explicitly determine the possible local-isometry types of manifolds that have the properties named above, but are not locally symmetric.AMS-TeX 2.1, 18 pages, no figures, submitted to an AMS volume of Proceedings in Contemporary MathematicsDifferential Geometry53B30text