This book deals with polarized optical spectroscopy of partially oriented fluid or rigid solutions. Starting from elementary concepts and relying on numerous illustrations, it provides an introduction to those interested in the measurement of the anisotropy of molecular optical properties in the UV, visible or IR regions (one- and two- photon absorption, simultaneous or sequential, luminescence, Raman scattering, natural and magnetic potical activity), or in the determination of uniaxial order and organization in supermolecular assemblies (liquid crystals, stretched polymers, membranes). The orienting effects of radiation (photoselection) are covered as well. A large number of examples of research applications within chemistry, biophysics, biochemistry, and polymer science are given together with examples of practical application.