The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are dealt with. Included are discussions of nonlinear wave mixing on films and surfaces, second harmonic generation in waveguides and at surfaces, nonlinear waves guided by dielectric and semiconductor surfaces and films, surface gratings formed by high energy laser beams, and reflection and transmission switching of strong beams onto nonlinear surfaces. Chapters on light scattering from surface excitations and magnetic order-disorder and orientational phase transitions complete this essential contribution to the modern optics literature.