  We review the progress made in understanding molecular cloud formation and
evolution toward star formation since the first Crete conference in 1990. It
now seems clear that molecular clouds in the Galaxy at least form from
compressed HI entering a spiral arm. The internal clumpy structure within
clouds probably results from the magnification of inhomogeneities in the
precursor HI. This structure is self-similar in nature independent of the star
forming nature of the cloud. However, at high densities and small scales, there
are departures from self-similarity that may be related to the mass scale of
stars. If confirmed, it may be that the mass of a star is related more to the
mass of the core from which it forms than by the details of the formation
process itself.
