  We present a detailed phenomenological study of spin-dependent
single-inclusive high-p_T hadron photoproduction with particular emphasis on
the kinematics relevant for the Compass and Hermes fixed-target experiments. We
carefully examine the theoretical uncertainties associated with the only
moderate transverse momenta accessible in such measurements and analyze the
sensitivity of the relevant spin asymmetries to the gluon polarization in the
nucleon as well as to the completely unknown parton content of circularly
polarized photons.
