This book provides an extended review on energetic particles interactions, propagation and acceleration in space plasmas. Its four chapters address key problems in CR Astrophysics and CR Geophysics. Chapter 1 briefly describes main properties of space plasmas and primary CR. Chapter 2 considers the problem of CR propagation in space plasmas. Chapter 3 is devoted to CR non-linear effects in space plasmas. In Chapter 4 different processes of CR acceleration in space plasmas are considered. The chapters contain analytical calculations, nonlinear physics and computer simulations. The book ends with a list providing more than 1,300 full references, a discussion on future developments and unsolved problems, as well as Object and Author indexes. This book will be useful for experts and students in CR research, Astrophysics and Geophysics, and in Space Physics.