Solid state studies of calixarenes and calix-type host molecules and their inclusion complexes are a source of information about geometry and interactions for both individual molecules and supramolecular complexes.  X-ray diffraction studies of crystalline samples provide direct information about molecular structure (atoms types and distribution, geometrical parameters, i.e. bond lengths, bond angles and torsion angles, molecular conformation and absolute configuration) and crystal structure (crystal composition, i.e. molecular ratio for complex crystals and/or presence of solvent(s) molecules, intermolecular interactions, especially determination of the networks of hydrogen bonds and short intermolecular contacts).  Solid state investigations are of great importance in particular in case of studying calixarene and calix-type compounds due to their great ability to form molecular inclusion complexes, co-crystals and supramolecular assemblies. In CSD (Cambridge Structural Database ) over 6000 structures of calix-type compounds are deposited so far. Approximately 1/3 of the entries are organometallic compounds and 2/3 are classified as organic compounds.  The analysis of over 4000 entries classified as organic compounds reveals that calixarene structures are in great majority (approx. 2900 entries). Among them about 2270 entries refers to calix[4]arenes.