The experimental data on the reactions of iodine atoms with olefins, alkyl halides, and oxygencontaining compounds (20 reactions) are analyzed under the model of intersecting parabolas (MIPs). The effect of the following factors on the activation energy of these reactions is found: the enthalpy of the reaction, triplet repulsion, and dipole–dipole interaction of the reaction site with the polar groups and π electrons of the neighboring double bonds. The increments characterizing the contribution from each factor to the activation energy are calculated.