An RNA has been selected that rapidly aminoacylates its 2’(3’) terminus when provided with phenylalanyl-adenosine monophosphate. That is, the RNA accelerates the same aminoacyl group transfer catalyzed by protein aminoacyl-transfer RNA synthetases. The best characterized RNA reaction requires both Mg2+ and Ca2+. These results confirm a necessary prediction of the RNA world hypothesis and represent efficient RNA reaction (greater than or equal to 10(5) times accelerated) at a carbonyl carbon, exemplifying a little explored type of RNA catalysis.