  An introduction to modern theories for the origin of structure in the
Universe is given. After a brief review of the growth of cosmological
perturbations in an expanding Universe and a summary of some important
observational results, the lectures focus on the inflationary Universe scenario
and on topological defect models of structure formation. A summary of the
theory and current observational status of cosmic microwave background
temperature fluctuations is given. The final chapter is devoted to some
speculative ideas concerning the connection between cosmology and fundamental
physics, in particular to ways in which the singularity problem of classical
cosmology may be resolved.
