This is a summary of the activities of the working group on cosmology at WHEPP-X. The three main problems that were discussed at some length by the group during the course of the workshop were (i) canceling a `large' cosmological constant, (ii) non-Gaussianities in inflationary models and (iii) stability of interacting models of dark energy and dark matter. We have briefly outlined these problems and have indicated the progress made.

Observations of the imprints of primordial gravitational waves on the anisotropies in the cosmic microwave background can provide us with unambiguous clues to the physics of the very early Universe. In this brief article, the implications of the detection of such signatures for the inflationary scenario has been discussed.