Short-range order has been investigated in Zr69.5Cu12Ni11Al7.5and Zr41.5Ti41.5Ni17metallic glasses using X-ray absorption spectroscopy andab initiomolecular dynamics simulations. While both of these alloys are good glass formers, there is a difference in their glass-forming abilities (Zr41.5Ti41.5Ni17> Zr69.5Cu12Ni11Al7.5). This difference is explained by inciting the relative importance of strong chemical order, icosahedral content, cluster symmetry and configuration diversity.