  We study the transresistivity $\tensor\rho_{21}$ (or equivalently, the drag
rate) of two Coulomb-coupled quantum wells in the presence of a perpendicular
magnetic field, using semi-classical transport theory. Elementary arguments
seem to preclude any possibility of observation of ``Hall drag'' (i.e., a
non-zero off-diagonal component in $\tensor\rho_{21}$). We show that these
arguments are specious, and in fact Hall drag can be observed at sufficiently
high temperatures when the {\sl intra}layer transport time $\tau$ has
significant energy-dependence around the Fermi energy $\varepsilon_F$. The
ratio of the Hall to longitudinal transresistivities goes as $T^2 B s$, where
$T$ is the temperature, $B$ is the magnetic field, and $s = [\partial\tau/
\partial\varepsilon] (\varepsilon_F)$.
