  The behavior of interfaces in the presence of both lattice pinning and random
field (RF) or random bond (RB) disorder is studied using scaling arguments and
functional renormalization techniques. For the first time we show that there is
a continuous disorder driven roughening transition from a flat to a rough state
for internal interface dimensions 2<D<4. The critical exponents are calculated
in an \epsilon-expansion. At the transition the interface shows a
superuniversal logarithmic roughness for both RF and RB systems. A transition
does not exist at the upper critical dimension D_c=4. The transition is
expected to be observable in systems with dipolar interactions by tuning the
temperature.
