Photo associated reactions and light responsive materials have great potential to improve existing industrial processes, including liquid crystal alignment and capturing solar energy. This book presents a range of reactions and materials with some of the most exciting current and future applications. It includes a brief introduction to phohemistry; in-depth discussion of photosensitizers, photoinititiators, and the processes of light curing and crosslinking; listing of light responsive polymers and their uses; and a discussion of polymeric materials for use in non-linear optics.