beta-Me elimination from cationic neopentyl complexes, [Cp'Zr-2(CH(2)CMe(3))](+), has been demonstrated. The more crowded complex (Cp' = C(5)Me(5)) eliminates isobutene instantaneously at -75 degrees C, whereas the less crowded analogue (Cp' = C5H5) is Stable in solution at 0 degrees C but undergoes reversible beta-Me elimination at 25 degrees C; strong anion or Lewis base coordination suppresses beta-Me elimination, consistent with involvement of a 14-electron species.