Kinetic effective molarities (EM) that quantify the increase in reaction rate for intramolecular formation of covalent bonds compared with the corresponding intermolecular process often have physically impossible values (up to 10¹³ M). It is therefore widely assumed that multivalent supramolecular systems could attain similarly large values of thermodynamic EM for formation of cooperative intramolecular noncovalent interactions. However, a survey of the literature shows that this is the exception rather than the rule. The majority of thermodynamic EM values for supramolecular complexes are in the range 1 mM–10 M. The largest values of EM found for supramolecular systems are of the order 10³ M in the most rigid highly preorganized assemblies.