  We investigate the quantum hadrodynamic equation of state for neutron stars
(with and without including hyperons) in the presence of strong magnetic
fields. The deduced masses and radii are consistent with recent observations of
high mass neutron stars even in the case of hyperonic nuclei for sufficiently
strong magnetic fields. The calculated adiabatic index and the moments of
inertia for magnetized neutron stars exhibit rapid changes with density. This
may provide some insight into the mechanism of star-quakes and flares in
magnetars.
