Some solvent extraction flowsheet development studies performed recently at Hanford Laboratories in support of the Hanford radioactive waste management and neptunium recovery programs are summarized. Flowsheet for the removal of cesium from Purex current waste and stored waste supernatant liquid are discussed. Dipicrylamine-nitrobenzene is used to extract cesium; dilute nitric acid is used to strip cesium from the organic. A one-cycle flowsheet for the removal of strontium and rare earth elements from Purex process waste and separation of these into a strontium and a rare earth fraction is discussed. Extraction of the desired elements from a citrate complexed feed is by di(2-ethylhexyl) phosphoric acid-tributylphosphate-Soltrol solvent. Strontium is removed from the organic by dilute nitric acid in the second column. Rare earths are stripped from the organic by more concentrated nitric acid in a third column. Procedures for recovery of neptunium and plutonium from Purex process acidic waste are described. The solvent is di(2-ethylhexyl phosphoric) acid-Soltrol; Pu(IV) and Np(IV) are extracted from acid solution at such high distribution ratios that adequate recovery is attained in a single batch contact. Studies leading to the flowsheets as well as results of tests of the flowsheets with simulated and actual plant solutions are discussed.