Several diglycolamide-functionalized calixarenes containing four and eight diglycolamide (DGA) moieties were evaluated for their relative extraction efficiencies towards Y(III) and Sr(II). Ligands containing four DGA units with n-propyl, iso-pentyl, and n-octyl groups at the amidic N atom adjacent to the calixarene skeleton showed efficient extraction of Y(III) from 3 M HNO3. The extraction of Sr(II) was poor in all cases in the entire acidity range (0.1–6 M HNO3) studied. The ligands with a hydrogen atom and an n-propyl group at the concerning amidic N atom showed a very high separation efficiency as reflected in separation factor (S.F.=DY/DSr) values in the range of 105–106. A method was developed for the separation of carrier-free 90Y from a 90Y-90Sr mixture involving consecutive extraction–stripping cycles. The product purity was checked using half-life measurements. Two consecutive cycles of extraction and stripping were found to be sufficient for obtaining pure 90Y. The results obtained in the present studies were compared with those obtained previously using analogous ligands such as TODGA (N,N,N',N'-tetraoctyl diglycolamide), T2EHDGA (N,N,N',N'-tetra-2-ethylhexyl diglycolamide), and PC-88A (bis(2-ethylhexyl) phosphonic acid).