The β effect of silicon, whereby a carbon-silicon bond substantially stabilizes an adjacent carbocation (Si-C-C+), has been widely studied mechanistically and exploited synthetically. 1-25 The phenomenon normally is invoked in reactive intermediates. Attempts to prepare stable Me3SiCH2CPh2 + under standard magic acid conditions led to loss of trimethylsilyl and observation only of CH3CPh2 +.11 A 2-(trimethylsilyl)allyl cation stable only at -100 °C did not comprise a β-effect system, as the silyl group destabilized the ion and the C-Si bond was orthogonal to the carbocation ð orbitals.21 Siehl and Kaufmann23 prepared 1-arylvinyl cations stabilized by β-silyl groups in magic acid at -120 °C. Persistent saturated β-silyl carbocations (by which we mean R3SiCH2- +C XY rather than R3SiCHd +C X), however, have never been observed by NMR, and the known unsaturated (vinylic23 and allylic21) examples are not stable in magic acid above about -100 °C. We report herein the preparation of a saturated β-silyl carbocation that is stable at room temperature.