Kinetics for the addition of the p-methoxybenzhydryl cation (AnPhCH+, 10) towards nonconjugated dienes 11 [H2C=C(CH3)-(CH2)n-C(CH3)=CH2] have been determined in CH2Cl2 at −30° to −70°C. Reactivity increases with increasing number of methylene groups separating the two double bonds. For N = 4, reactivity reaches the value for saturated alkyl substituents, and nucleophilic assistance of the second double bond is never observed.