Solid form selection is a critical part of the development of a pharmaceutical compound. The presence of a crystalline drug substance provides improved bulk properties, whereas the use of a salt of a pharmaceutical compound can provide enhanced properties such as increased dissolution rate. Owing to different crystal structures, polymorphic forms of a compound have different physical and chemical properties, which can affect the biopharmaceutical properties of a pharmaceutical compound. The selection of the optimum salt and physical form for development utilises a wide range of analytical procedures and laboratory skills. This book provides an up-to-date review of the current techniques used to characterise pharmaceutical solids. It will serve as a vital resource for analysts, and essential reading for scientists involved in solid form selection.