Results important for the general understanding of nuclear structure have emerged from the study of the nuclei in the mass region around the neutron-deficient and neutron-rich Zirconium isotopes. This research report gives the proceedings of a workshop which brought together about 70 experts in the area. Review papers deal with the theoretical interpretation of the unusual properties of these medium-mass nuclei, using the mean field approach, a microscopic description, the interacting boson model and particle rotor calculations. Papers also discuss experimental procedures for studying nuclei...