  We present our recent analysis on the transverse single-spin asymmetry (SSA)
in inclusive pion and direct-photon production in pp collisions for RHIC
kinematics. The analysis includes the contributions from twist-3
quark-gluon-quark correlations in the proton and twist-3 fragmentation effects
for the pion. Some of the functions appearing in the formula for the SSA, such
as the soft-gluon-pole Qiu-Sterman function, the nucleon transversity, and the
Collins function were fixed consistently with the SSA data in semi-inclusive
DIS and in e+e- annihilation, so that our analysis is free from the sign
mismatch problem.
