We consider a model in which magnetars arise from a high baryon density, magnetized core which forms when they are born. In this framework, magnetars are distinguished from pulsars by their higher masses and central density. In this model for magnetars, as core densities exceed a threshold, the strong interaction can induce a phase transition to a ground state that aligns nucleon magnetic moments. The core magnetic field is initially shielded by the ambient high-conductivity plasma. With time the shielding currents dissipate transporting the core field out, first to the crust and then breaking through the crust to the surface of the star. Recent observations provide support for this model which accounts for several properties of magnetars and also enables us to identify new magnetars.