Quality Assessment of the CSP Results. We propose that the dataset of predicted crystal structure landscapes across a large, diverse set of molecules is valuable for the development of future predictive models. To evaluate the quality of the dataset, we assess three aspects: completeness of the landscapes; how well, geometrically, the CSP calculations reproduce the known crystal structures of these molecules and the quality of the relative energies of the predicted structures. The 26 space groups included in our standard search include those with an observed frequency above 0.05 % in the CSD. Naturally, in a very large survey of molecules, we include some that crystallise in less frequent space groups; for these 8 cases, we added the space group of the observed crystal structure to the search. In 3 additional cases, the symmetry of the observed structure means that it could not have been sampled without performing CSP with multiple independent molecules (Z' > 1); in these cases, we include the datasets in our study, knowing that the observed crystal structures could not have been located. Of those that could have been located, the searches find matches for 1034 of the 1040 observed crystal structures: reasons for the 6 missed matches are discussed below. A main assumption in CSP is that the observed crystal structures of a molecule correspond to the lowest energy possible structures. We use this assumption to assess the quality of the calculated energies. tures of form I paracetamol . 327 matches have RMSD 30 below 0.204 Å, i.e. have geometric deviations that are of a magnitude that can be explained by the temperature-free nature of structural optimisations used in CSP. While known crystal structures are reproduced very well by CSP in most cases, there are a small number where agreement is less satisfactory: in 32 cases (3 % of structures), RMSD 30 > 1 Å. Despite what might be assumed, we find no significant correlation between the RMSD 30 of the experimental match and the molecular RMSD of the parent gas-phase conformer used for CSP. Assuming an experimental match is found, the geometric quality of the match is only weakly sensitive to the difference in the molecular conformation used for CSP; even the most extreme outlier in molecular conformational change (the aforementioned DOBYOJ) achieves a reasonable geometric match to the experimental crystal structure, with RMSD 30 = 0.654 Å.