Combining the expertise of a leading experimentalist and a foremost theorist,this textbook presents all relevant aspects of both observational cosmology and related theoretical concepts. In addition to the more descriptive sections where the reader is able to get the flavor of the subject without needing to follow every step involved, some chapters contain optional more technical parts. The book is self-contained and requires no prior knowledge other than basic undergraduate mathematics and physics. This and the inclusion of worked examples, end- of-chapter summaries, and problems (with answers) in each chapter make this book an excellent introduction to particle astrophysics for advanced undergraduate students. The second edition includes the newest developments on the cosmic microwave background anisotropy, the measurement of the Hubble constant, gravitational lensing experiments and neutrino oscillations.