The discovery of new materials is important for addressing many critical societal needs, including energy production and storage, pollution remediation and healthcare. Research endeavours aimed at improving the success and efficiency of functional materials discovery, based on traditional efforts developing our understanding of the rules of crystal packing and, more recently, applications of machine learning, have benefited greatly from the availability of databases of stable crystal structures. A major resource for such efforts has been the growth of accessible, curated databases of crystal structures and (some of) their properties. The most general and widely-used include the Cambridge Structural Database (CSD) for organic and organometallic systems, and the Inorganic Crystal Structure Database . These resources are unparalleled in their volume of experimental crystal structure information, but do not currently offer information about calculated or hypothetical structures. Historically, such data was limited to specialised areas (such as the Atlas of Prospective Zeolite Structures (3)), though recent developments have made remarkable progress in generalising this concept, including extensions to the Crystallography Open Database (COD)(4-7) and the Materials Project . In the field of organic molecular crystals, however, much of our understanding of the rules of crystal packing derive from databases of experimentally observed structures. Modern computational chemistry, employing both molecular and solid-state simulation techniques, can add significantly to the information that is available from experimentally determined crystal structures, and identify previously unverifiable trends. Computational studies of polymorphism have evaluated the typical lattice energy differences between crystalline polymorphs of organic molecules, studies of conformations of flexible molecules in their observed crystal structures have improved understanding of the limits of molecular strain in stable structures, and studies of the thermodynamics of co-crystallisation have aided in rationalising a complex phenomenon with ramifications for experimental design.