This book describes metamorphic rock formation mechanisms in a simplified form. It presents the geometrical rules which control mineral assemblages as a function of rock composition, and provides the basis of a thermodynamical approach used for equilibrium slope calculations as well as for the evaluation of P, T stability fields of mineral associations. On the basis of several examples from the literature, the author emphasizes the relations between different metamorphic gradients and different geodynamic situations. Associated P-T-t paths are examined from several points of view including the respective roles of heat conduction and convection. Audience: This textbook will be useful to undergraduate students in geology, but also to research students and scientists needing to rapidly update their knowledge of metamorphism. It is also accessible to anybody interested in geosciences wanting to acquire a basic knowledge of the close relationships that exist between geodynamics and metamorphic processes.