This book provides a comprehensive and unified account of the structure and properties of crystalline binary adducts. Perhaps better known as molecular complexes and compounds, these crystals are currently estimated (from molecular recognition studies) to make up one quarter of the world's crystals, providing evidence for some sort of special attraction between the two components. DNA is perhaps the most famous example but others (hydrates, solvates, host-guest inclusion complexes, donor-acceptor compounds) pervade the whole body of solid state chemistry. Although much research has been published, there has never been a comprehensive and unified treatment of the whole field. This book has been designed to fill this gap, comparing and contrasting the various examples and the different types of interaction (hydrogen bonding, inclusion and localized or delocalized charge transfer). More than 600 figures, 200 tables and 3500 references are included in the book. Since most 'parent compounds' form a number of adducts, the fraction of crystalline binary adducts is only going to grow making this account just the 'tip of the iceberg'.