  The electronic structure of some europium chalcogenides and pnictides is
calculated using the {\it ab-initio} self-interaction corrected
local-spin-density approximation (SIC-LSD). This approach allows both a
localised description of the rare earth $f-$electrons and an itinerant
description of $s$, $p$ and $d$-electrons. Localising different numbers of
$f$-electrons on the rare earth atom corresponds to different nominal
valencies, and the total energies can be compared, providing a first-principles
description of valency. All the chalcogenides are found to be insulators in the
ferromagnetic state and to have a divalent configuration. For the pnictides we
find that EuN is half-metallic and the rest are normal metals. However a
valence change occurs as we go down the pnictide column of the Periodic Table.
EuN and EuP are trivalent, EuAs is only just trivalent and EuSb is found to be
divalent. Our results suggest that these materials may find application in
spintronic and spin filtering devices.
