Photodissociation induced by the absorption of single photons permits the detailed study of molecular dynamics such as the breaking of bonds, internal energy transfer and radiationless transitions. The availability, over the last decade, of powerful lasers operating over a wide frequency range has stimulated rapid development of new experimental techniques which make it possible to analyse photodissociation processes in unprecedented detail. At the same time, theorists have developed powerful methods to treat this fundamental process, at least for small molecules, in an essentially exact quantum mechanical way. The confluence of theory and experiment has greatly advanced understanding of molecular motion in excited electronic states. This text elucidates the achievements in calculating photodissociation cross-sections and fragment state distributions from first principles, starting from multi-dimensional potential energy surfaces and the Schrödinger equation of nuclear motion. Following an extended introduction in which the various types of observables are outlined, the next four chapters summarise the basic theoretical tools, namely the time-independent and the time-dependent quantum mechanical approaches as well as the classical picture of photodissociation. The discussions of absorption spectra, diffuse vibrational structures, the vibrational and rotational state distributions of the photofragments form the core of the book. More specific topics such as the dissociation of vibrationally excited molecules, emission during dissociation, or nonadiabatic effects are discussed in the last third of the book. Photodissociation Dynamics will be of interest to graduate students as well as senior scientists working in molecular physics, spectroscopy, molecular collisions and molecular kinetics.