This book gives an introduction to applications of rock mechanics within the petroleum industry. It is well suited as a textbook for engineers and researchers entering the field, and for MSc/PhD level university students. The book starts with a general introduction to rock mechanics, kept at a moderate mathematical level. This part covers elasticity, poroelasticity and rock failure theory, as well as geological aspects of rock mechanics. The book further describes a variety of laboratory and field techniques for estimation of rock mechanical parameters and Earth stresses, and gives a comprehensive overview of acoustic wave propagation in rocks. The last four chapters of the book are devoted to industrial use of rock mechanics within drilling, production and reservoir engineering. These chapters are brought up to date by incorporating novel research results and applications.