  One of the primary goals of the spin program at the Relativistic Heavy Ion
Collider (RHIC) is to determine the polarization of the sea quarks and gluons
in the proton. The polarization of the sea quarks is probed through the
production of $W^{-(+)}$ bosons via the annihilation of
$\bar{u}+d\,(\bar{d}+u)$, at leading order. In this proceedings we report
measurements of the single-spin asymmetry, $A_{L}$, for $W$ boson production at
$\sqrt{s} = 510$ GeV, and the new constraints these results place on the
antiquark helicity distributions. Recent results on the longitudinal
double-spin asymmetry, $A_{LL}$, for inclusive and di-jet production at
$\sqrt{s} = 200$ GeV are also presented. The inclusive jet results provide the
first experimental indication of non-zero gluon polarization in the $x$ range
probed at RHIC.
