A targeted particulate, synthetic organic plastic material having normally hydrophobic surface characteristics is separated from a mixture of two or more of such plastic materials by conditioning the mixture of plastic materials in a flotation cell with a heteropolar surfactant which has a hydrophile-lipophile balance (HLB) value greater than 5 and which selectively depresses the targeted plastic material by making the surfaces thereof more hydrophilic without substantially affecting the surfaces of the other plastic material(s) and introducing gas bubbles into the resulting conditioned pulp such that the gas bubbles selectively adhere to the surfaces of the other plastic materials(s) and cause them to float. The targeted plastic material is recovered in the cell product and the other plastic material(s) is recovered in the float concentrate.