A systematic study of isotope chains in the rare–earth region is presented. The energy levels, E2 transition rates, and two–neutron separation energies are described by using the most general IBM-1 Hamiltonian for the chains For each isotope chain a general fit is performed in such a way that all parameters but one are kept fixed to describe the whole chain.In this region nuclei evolve from spherical to deformed shapes and a method based on catastrophe theory, in combination with a coherent state analysis to generate the IBM-1-1 energy surfaces, is used to identify critical phase transition points