The solubility, spectral, and kinetic methods were used to study complexing between α-cyclodextrin (ligand, L) and 3,5-dimethoxycinnamic acid, benzalacetone, and methyl cinnamate (substrates, S). In aqueous solution at 25° and with an ionic strength of 0.01 M, the following stability constants were found (K11 for SL and K12 for SL2): 3,5-dimethoxycinnamic acid, K11 = 1965 M1 and K12 = 0; benzalacetone, K11 = 105 M−1 and K12 = 15 M−1; and methyl cinnamate, K11 = 1200 M−1 and K12 = 50 M−1. A model of complex formation is proposed that can account for the observed stoichiometry and that yields stability estimates for two isomeric 1:1 complexes in the systems in which a 1:2 complex forms. For cinnamic acid, benzalacetone, and methyl cinnamate, stability constants are inversely correlated with the substrate dipole moment.