Interstellar and solar system solids are different stages of the same materials. In this book, the sources and evolution of circumstellar dust, interstellar dust, comets, meteorites and interplanetary dust are carefully discussed in the context of their interrelations. One of the major questions raised is: how do characteristically 1/10 micron interstellar dust particles evolve to rocky materials 1000 times larger or more? The closest we appear to be getting in relating interstellar dust to particles in the solar system is the evidence for submicron organic coated particles in interplanetary dust particles collected in the upper atmosphere, which allow direct laboratory investigation on Earth. What we know about comets, however, either results from remote observation or space measurements in situ. Comet volatiles compare very well with interstellar ices. These astrophysical problems bring to bear a very wide range of theoretical, observational and laboratory expertise in such fields as astronomy, physics and chemistry and, with the evidence of complex prebiotic organics in meteorites.