The role of hydrogen bonding in the packing of a variety of carboxyl acid amides is investigated - p-amide-benzoic, phenylamido carboxylic, benzoylamino carboxylic, phthalamido carboxylic acids and carboxytrimellitimides. A variety of arrangements are observed with both amide-amide and acid-acid hydrogen bonds as well as acid-amide interactions. In certain cases alternative packing arrangements appear possible with the structure finally adopted being determined by the length of the alkyl chain in the molecule.