  We present the results of a detailed study of the large transverse momentum
Drell-Yan process, pp --> (Gamma^*, Z^*)X --> l^+l^- X at collider energies,
with either one or both protons polarised, allowing the study of single- and
double-spin asymmetries respectively. We show how these asymmetries obtained
from angular distributions of the leptons in the Gamma^* (or Z^*) rest-frame,
can be used to get information on the polarised parton distributions. Numerical
results for the asymmetries and the cross-sections are presented, and the
sensitivity of the asymmetries to the initial parton distributions indicates
that these can be used as effective probes of the spin structure of the proton.
