Abstract: A photosensitive printing medium is compounded from a latex copolymer, a linear thermoplastic, elastomeric block copolymer, a basic nitrogen atom-containing compound, an ethylenically unsaturated compound, and a polymerization initiation system. The printing medium has a microstructure of distinct domains of the latex copolymer and the elastomeric block copolymer in a matrix of the other components. The printing medium is typically supported on a substrate to form a printing plate. The printing medium is photosensitive, and is imaged by exposure to actinic radiation through a photographic negative film. The unexposed portions are washed away in a water dispersive medium, without the use of organic solvents, producing a printing plate which, after drying and postexposure to UV light, is ready for printing.