We use a “pairing fluctuation” approach to address the behavior ofTcand pseudogap ind-wave superconductors. This theory yields a BCS-Bose-Einstein crossover description of the superconducting transition, which reduces to BCS in the weak coupling (smallg) limit and to a Bose-Einstein description at largeg. We investigate the effects of quasi-two dimensionality, lattice bandstructure andd-wave symmetry, and obtain a cuprate phase diagram, in quantitative agreement with experiment. ©1999 American Institute of Physics.