Photoinitiated Polymerization is divided into five sections. Free radical photopolymerizations command most of the interest and activity within the field and thus is discussed first. The second section discusses kinetic studies of the mechanism of free radical polymerizations. The third section covers cationic photopolymerizations, which along with free radical polymerizations, are being used in many industrial applications. The fourth section is devoted to recent developments in novel photopolymeriztion chemistry. This section describes new photobase generators, developments in monomers, oligomers and templated polymerizations of liquid crystal polymers. Finally, the fifth section portrays new and emerging applications for photopolymerizations.