[en] After ether extraction was scaled up to plant status, solvent extraction grew rapidly, intensively, and extensively. This paper recounts developments at the ORNL in three fields: Fuel Reprocessing, Uranium Production, and Transplutonium Element Recovery. Fuel Reprocessing: In the late 1940's, soon after TBP was discovered to be an extractant, the Purex process was developed to recover, decontaminate, and separate Pu and U (from nitric acid solutions of spent reactor fuels) without the need of added salting agents. Uranium Production: Around 1950, the ORNL Raw Materials Section launched an intensive search for reagents that could extract uranium from sulfuric acid leach liquors. This was accomplished with di(2-ethylhexyl)phosphoric acid (HDEHP) and a suite of high-molecular-weight alkylamines. The resulting Dapex and Amex processes eventually dominated domestic uranium production, spread world-wide, and provided bases for innovative processes in other fields. Transplutonium Element Recovery: Tramex and Talspeak processes accomplish separation of the trivalent actinides from the similar lanthanides. Tramex (1961; amine extraction from concentrated lithium chloride) has been used in the ORNL Transuranium processing Plant (TRU) since 1966. Talspeak (1964; HDEHP extraction from carboxylic acid + aminopolyacetate complexer) has wider potential because it is less corrosive, and it is being extensively studied for separating americium and curium from fuel reprocessing wastes