  The theoretical status of the `proton spin' effect is reviewed. The
conventional QCD parton model analysis of polarised DIS is compared with a
complementary approach, the composite operator propagator-vertex (CPV) method,
each of which provides its own insight into the origin of the observed
suppression in the first moment of $g_1^p$. The current status of both
experiment and non-perturbative calculations is summarised. The future role of
semi-inclusive DIS experiments, in both the current and target fragmentation
regions, is described.
