The oxide superconductors La2-xSrxCuO4 and YBa2Cu3O6.5+y are treated as strongly correlated electron systems consisting of Cu ions with an on-site electron-electron interaction U of order 10 eV interacting via oxygen bands. Pairing occurs via scattering of quasiparticles into the two-particle resonance at energy U. The model is expressed in a slave-boson formalism and solved in mean field. The results explain the observed scaling of Tc with hole concentration and are consistent with other data. © 1987 The American Physical Society.