This book is a collection of lectures given in August 2006 at the Les Houches Summer School on "Particle Physics and Cosmology: the Fabric of Spacetime. It provides a pedagogical introduction to the various aspects of both particle physics beyond the Standard Model and Cosmology of the Early Universe, covering each topic from the basics to the most recent developments.· Provides a pedagogical introduction to topics at the interface of particle physics and cosmology· Addresses each topic from the basis to the most recent developments· Provides necessary tools to build new theoretical models addressing various issues both in cosmology and particle physics· Covers the lectures by internationally-renowned and leading experts· Faces the predictions of theoretical models against collider experimental data as well as from cosmological observations