The electronic stability of Al-1%Mg 2 Si(Fe) after various age-hardening treatments is investigated. After studying the AlL 2 , 3 soft X-ray emission spectra and comparing these to a DTA scan of the alloy, we conclude there is a correlation between the age-hardening process and the electronic state of the alloy. We believe that this correlation is of general applicability and should help focus attention on the interdependence of the thermal stability and electronic structure of the metastable alloys.