The author gives a comprehensive account of Langrangian fluid dynamics. Starting from the foundations of elementary kinematics and assuming some familiarity with Eulerian framework, he then discusses the general solvability of the resulting general equations of motion. A unified account of turbulent diffusion and dispersion has been given, with applications among others to plankton patchiness in ocean. The book will be of interest to applied mathematicians, oceanographers, meteorologists, mechanical engineers, astrophysicists and all investigators of the dynamics of fluids.