Temperature-dependent Berry pseudorotation rate constants of SF4 gas at ca. 7.9 atm, determined from analysis of exchange-broadened F-19 NMR spectra, are consistent with E-infinity = 11.9(0.2) kcal mol(-1), A(infinity) = 3.56(1.09) x 10(12) s(-1): Delta G(298)(double dagger) = 12.2(0.1) kcal mol(-1), Delta H-298(double dagger) = 11.3(0.4) kcal mol(-1), and Delta S-298(double dagger) = -3.3(0.4) cal mol(-1) K-1. Using a 6-31+G* basis set, HF calculations predict Delta H-298(double dagger) = 12.26 kcal mol(-1) and Delta S-298(double dagger) = -3.74 cal mol(-1) K-1 and MP2 calculations predict Delta H-298(double dagger) = 9.99 kcal mol(-1) and Delta S-298(double dagger) = -3.89 cal mol(-1) K-1. Stationary point MP4/6-31+G*//HF/6-31+G* calculations predict Delta H-298(double dagger) = 11.55 kcal mol(-1) and Delta S-298(double dagger) = -3.91 cal mol(-1) K-1. DFT calculations using the 6-31+G* basis set and the B3LYP and B3PW91 hybrid functionals are considerably less accurate. Pressure-dependent rate constants obtained at 335 K agree well with RRKM theory predictions using the strong collision assumption. The curvature and displacement of the experimental falloff curve are not significantly perturbed by effects of weak collisions and/or nonstatistical intramolecular vibrational energy redistribution.