A strong enhancement of electron-ion recombination over expected rates at sub-eV relative energies is revealed for highly charged ions. Measured Ne' + and Ar' + recombination rates were found to be enhanced at low (&1 rneV) energies by factors of 4 and 10 over theoretical predictions of radiative recombination rates, respectively.It is shown that the majority of the enhancement in Ar' is caused by very low lying An = 0 dielectronic recombination resonances; nevertheless, the nonresonant contributions to the measured recombination rates for both systems were found to be significantly higher than predicted by presently available models.PACS numbers: 34.80.Kw, 32.80.HdAmong the fundamental electron-ion interactions which occur in plasmas [1,2], recombination at low energies has turned out to be surprisingly unpredictable.Measurements performed under the most precise conditions yet achieved have consistently yielded experimental rates far above theoretical expectations [3 -6]. No convincing explanation of these enhanced rates exists, nor have detailed quantitative spectra in the sub-meV region been presented.In models describing recombination in electron coolers one considers three basic processes: radiative recombination (RR), where energy and momentum conservation is balanced by the emission of a photon, e + a '-A" "'+ hv, three-body recombination (TBR), where the excess energy is imparted to a neighboring free electron, e +e +A+ A~'~+ e and, for nonbare ions, dielectronic recombination (DR), where a free electron is captured resonantly with the excitation of a bound electron in the ion. This process can be viewed as the time reverse of Auger emission.