Carbanions are anions that have a carbon center with an unshared pair of electrons and a formal negative charge. Understanding the reactivity of carbanions is challenging because it depends upon the associated metal and is sensitive to additives, the solvent, temperature, and concentration. Complications in solution due to solvation, counterion effects, and aggregation have hindered our understanding of these species. As a result, the intrinsic reactivity and properties of isolated and truly free carbanions in the gas phase are of interest. Versatile synthetic strategies have been developed for the preparation of a wide variety of gaseous carbanions. This has enabled the reactivities and thermodynamic properties of many carbanions to be experimentally determined. Moreover, because the electron can be viewed as the simplest protecting group, the reactivities and energetics of neutral species such as radicals, biradicals, carbenes, and other fleetingly stable species also can be explored.