Self-consistent spin-polarized calculations of the electronic and magnetic structure of amorphous Fe x B 1− x alloys, based on realistic models of the glass-structure generated by a simulated molecular-dynamics quench using tight-binding-bond forces between the atoms, are presented. The calculations predict average the moments in good agreement with experiment and small negative magnetic moments on the B sites whose origins are in a covalent coupling of the B p-states to the Fe spin-down band. In the glass richest in Fe, a few sites acquire a negative moment. It is found that the formation of negative Fe moments is due to a local-environment effect.