  We report the polarized parton distributions proposed by the Asymmetry
Analysis Collaboration (AAC). Using parametrized distributions at Q^2=1 GeV^2
and measured A_1 data, we determine optimum polarized distributions in the
leading order (LO) and next-to-leading order (NLO). We find that the polarized
antiquark distribution is not well determined particularly at small x. It could
lead to a rather small quark spin content in comparison with usually-quoted
values of 10-30%. In our analysis, it varies from 5% to 28% depending on the
small-x extrapolation. It is necessary to have small-x (<10^{-3}) data for
precise determination. In addition, the large-x region should be also studied
for \Delta q-bar, which cannot be determined solely by g_1. We propose three
sets of distributions as the longitudinally polarized parton distribution
functions.
