  We present our recent studies of the pseudo-critical temperature, $T_c$, of
QCD using domain wall fermions. Domain wall fermions have the advantage that
they preserve exact SU(2) chiral symmetry at finite lattice spacing in the
limit that $L_s \to \infty$. The RBC Collaboration has performed a set of
dynamical calculations at $L_s = 32$ and $N_t = 8$ using the Iwasaki gauge
action with two light quarks ($m_l a = 0.003$) and one strange quark ($m_s a =
0.037$). A clear signal for the crossover transition can be seen in the light
chiral susceptibility, as well as in the Wilson line. However, at $L_s = 32$,
the residual chiral symmetry breaking is not yet fully under control. We also
present preliminary results from the HotQCD Collaboration with $N_t = 8$ and
$L_s = 96$, where the effects of the residual chiral symmetry breaking are
reduced compared to $L_s = 32$.
