Integrable boundary conditions are constructed for the critical A-D-E lattice models of statistical mechanics. In particular, using techniques associated with the Temperley-Lieb algebra and fusion, a set of explicit boundary Boltzmann weights which satisfies the boundary Yang-Baxter equation is obtained for each boundary condition. When appropriately specialised, these boundary weights, each of which depends on three spins, decompose into more natural two-spin edge weights. The specialised boundary conditions are also naturally in one-to-one correspondence with the conformal boundary conditions of sl(2) unitary minimal conformal field theories. Supported by this and further evidence, we conclude that, in the continuum scaling limit, the integrable boundary conditions provide realisations of the complete set of conformal boundary conditions in the corresponding field theories