  Aspects of string cosmology for critical and non-critical strings are
discussed emphasizing the necessity to account for the dilaton dynamics for a
proper incorporation of ``large - small" duality. This drastically modifies the
intuition one has with Einstein's gravity. For example winding modes, even
though contribute to energy density, oppose expansion and if not annihilated
will stop the expansion. Moreover we find that the radiation dominated era of
the standard cosmology emerges quite naturally in string cosmology. Our
analysis of non-critical string cosmology provides a reinterpretation of the
(universal cover of the) recently studied two dimensional black hole solution
as a conformal realization of cosmological solutions found previously by
Mueller.
