  The results of a recent next-to-leading order QCD analysis of the world data
on polarized deep inelastic scattering are reported. New parameterizations are
derived for the quark and gluon distributions and the value of
$\alpha_s(M_z^2)$ is determined. We obtain $\alpha_s^{\rm NLO}(M_Z^2)=
0.1132~~\begin{array}{l} + 0.0056 \\ -0.0095 \end{array}$. Potential higher
twist contributions to the structure function $g_1(x,Q^2)$ are considered.
