[en] A theory of pairing in weakly bound nuclei is presented. The nucleus is treated as a three-body system consisting of two interacting nucleons together with a structureless core. The pairing interaction is modelled by a density-dependent contact interaction. It is constrained to the free nucleon interaction at low density. Numerically, the Hamiltonian equation is solved by a two-particle Green's function method in coordinate space. Given the single particle resonance energy of ¹⁰Li, the theory reproduces the marginal binding of ¹¹Li. The large electric dipole stength in ¹¹Li found experimentally is also accounted for. The nucleus ¹⁴Be is also found to be bound. copyright 1991 Academic Press, Inc