  We report on the MILC collaboration's calculation of $f_B$, $f_{B_s}$, $f_D$,
$f_{D_s}$, and their ratios. Our central values come from the quenched
approximation, but the quenching error is estimated from $N_F=2$ dynamical
staggered lattices. We use Wilson light valence quarks and Wilson and static
heavy quarks. We find, for example, $f_B=157 \pm 11 {}^{+25}_{-9} {}^{+23}_{-0}
\MeV$, $f_{B_s}/f_B = 1.11 \pm 0.02 {}^{+0.04}_{-0.03} \pm 0.03$, $f_{D_s} =
210 \pm 9 {}^{+25}_{-9} {}^{+17}_{-1} \MeV$ and $f_{B}/f_{D_s} = 0.75 \pm 0.03
{}^{+0.04}_{-0.02} {}^{+0.08}_{-0.00}$, where the errors are statistical,
systematic (within the quenched approximation), and systematic (of quenching),
respectively.
