Superstring theory promises to unify all four forces of nature at the quantum
level. Therefore, superstring theory should play an important role in early universe
cosmology. I will argue that taking into account new degrees of freedom and new symmetries
which distinguish string theories from point particle theories will lead to a non-singular
early universe and a new mechanism of cosmological structure formation which is consistent
with current data but makes interesting predictions for future observations, in particular
for the spectrum of primordial gravitational waves.