A general rule, previously derived for a complex between an achiral guest compound and a chiral macrocyclic host compound, can explain the inversion of circular dichroism (CD) signs observed in the complexation of 2-substituted naphthalenes (2-naphthol, 2-methylnaphthalene, 2-chloronaphthalene, 6-bromo-2-naphthol) with alpha- and beta-cyclodextrins, where the substrates are included deeply in the cavity of beta-cyclodextrin but only partly included in the cavity of or-cyclodextrin. The present success of the general rule supports its validity and usefulness.