Rigorous quantum chemical investigations of the S(N)2 identity exchange reactions of methyl, ethyl, propyl, allyl, benzyl, propargyl, and acetonitrile halides (X = F-, CI-) refute the traditional view that the acceleration of S(N)2 reactions for substrates with a multiple bond at C-beta (carbon adjacent to the reacting C-alpha center) is primarily due to pi-conjugation in the S(N)2 transition state (TS). Instead, substrate-nucleophile electrostatic interactions dictate S(N)2 reaction rate trends. Regardless of the presence or absence of a C-beta multiple bond in the S(N)2 reactant in a series of analogues, attractive C-beta(delta(+)) ... X(delta(-)) interactions in the S(N)2 TS lower net activation barriers (E-b) and enhance reaction rates, whereas repulsive C-beta(delta(-)) ... X(delta(-)) interactions increase Eb barriers and retard S(N)2 rates. Block-localized wave function (BLW) computations confirm that pi-conjugation lowers the net activation barriers of S(N)2 allyl (1t, coplanar), benzyl, propargyl, and acetonitrile halide identity exchange reactions, but does so to nearly the same extent. Therefore, such orbital interactions cannot account for the large range of E-b values in these systems.