Pang (U. of Electronic Science and Technology of China) and Feng (National U. of Singapore) explain the properties of microscopic particles in nonlinear systems and the principles of the nonlinear quantum mechanical theory for an audience ranging from researchers to upper level undergraduate students. They also explore applications in condensed matter, polymers, and biological systems. Ten chapters cover macroscopic quantum effects, a proposed theory of nonlinear quantum mechanics, the wave-corpuscle duality of particles in nonlinear systems, mechanisms of nonlinear interactions and their relations to localization of particles, comparative features of nonlinear and linear quantum mechanical theories, methods of solving nonlinear quantum mechanical systems, dynamic properties of microscopic particles in different nonlinear systems, and applications in the various physical systems mentioned above.