A study of plasma equilibrium and stability in a tokamak with an unsaturated iron cpre is presented. A spool model is developed for the iron core. Both a simplified force balance code and a Grad-Shafranov solver are used to study the plasma equilibrium. It is observed that the iron can strongly modify the conditions for equilibrium and stability, and in some cases an infinite cylinder model for the iron core is not adequate. Corrected criteria for plasma position stability in the presence of an iron core are introduced.