Classical novae - Contributions to the interstellar medium

Theoretical results predicting yields of various isotopes in nova outbursts are reviewed. Emphasis is placed on the stardust and gas-phase chemical anomalies that may be contributed to the Galactic ISM by classic novae. It is concluded that most of the heavy isotope anomalies are produced by about 25 percent of novae that occur in systems containing massive O-Ne-Mg white dwarfs. The dust-production scenario for novae is summarized, and it is argued that explosions on O-Ne-Mg white dwarfs may lead to the formation of dust grains that carry the Ne-E and Mg-26 anomalies. Quantitative constraints are placed on the degree to which classical novae participate in the production of chemical anomalies, both in the primitive solar system and on a Galactic scale.