The papers in this volume were presented at the Second International Conference on Unconventional Photoactive Solids held at the R&D Center of BP America September 9-12, 1985. It was part of an on-going series of conferences with the main aim of stressing the Interrelationship of solid state physics and solid state chemistry. The choice of topics covered a broad range of light-Induced solid state phenomena with particular emphasis on novel materials and/or novel phenomena. Organic solids, in particular, were emphasized as they are a natural meeting point of solid state physics and chemistry. A general trend In solid state physics Is to more complex materials (e.g. nonequilibrium glassy films, complicated unit cells, extended molecular building blocks, etc.). This trend necessitates the closer interaction between physicists and chemists. This conference reflects this trend quite dramatically. It is a new grouping together of a mix of materials, people and experimental approaches. A typical new theme pulling together this new mix can be seen in Part I. Fractals in Disordered Media. A variety of disordered media give rise to unusual temporal patterns of diffusion and reactions. The more familiar spatial patterns of self-similarity are discussed in the first article by M.F. Barnsley. Another topic pulling together a diverse group of scientists is covered in Part II. Spectral Hole-Burning. A number of leaders in this field are represented In these three papers.