  We perform next-to-leading order global analyses of deep inelastic and
related data for different fixed values of $\alpha_S (M_Z^2)$. We present sets
of parton distributions for six values of $\alpha_S$ in the range 0.105 to
0.130. We display the $(x, Q^2)$ domains with the largest parton uncertainty
and we discuss how forthcoming data may be able to improve the determination of
the parton densities.
