  Galactic disk formation requires knowledge about the initial conditions under
which disk galaxies form, the boundary conditions that affect their secular
evolution and the micro-physical processes that drive the multi-phase
interstellar medium and regulate their star formation history. Most of these
ingredients are still poorly understood. Recent high-resolution observations of
young high-redshift disk galaxies provide insight into early phases of galactic
disk formation and evolution. Combined with low-redshift disk data these
observations should eventually allow us to reconstruct the origin and evolution
of late-type galaxies. I summarize some of the major problems that need to be
addressed for a more consistent picture of galactic disk formation and
evolution.
