Vinylcyclopropane (1) is deprotonated in the gas phase by NH2 - or Me2N- to afford its conjugate base (1a). Vinylcyclopropyl anion is quite basic (ΔHacid(1) = 394 ±3 kcal mol-1), has a relatively small electron binding energy (12 ± 5 kcal mol-1), and reacts with a variety of reagents including N2O, CS2, COS, O2, and SO2. The reaction of 1 with OH- (ΔHacid(H2O) = 390.7 kcal mol-1) leads to a surprising rearrangement and the formation of the conjugate base of methylenecyclobutane (2a). A mechanism is proposed to account for this unusual reaction and it is in accord with ab initio molecular orbital calculations. In particular, the orbital symmetry allowed (σ2s + π4s) transition state leading to 2a is slightly preferred over the conrotatory ring opening of 1a (1.2 kcal mol-1 (MP2/6-31+G*//6-31+G*)).