Equilibria with minimum energy are constructed from a variational principle in which the potential energy of a plasma is minimized, subject to a small set of global invariants. These invariants are preserved exactly, by ideal motions of the plasma, and approximately, by a tearing mode of them=1,n=1 type. Estimates of decay rates for the energy and the invariants are given. A tokamak window with lowqand zero current on the boundary is found and shown to be ideally and resistively stable. The reversed‐field pinch (RFP) window and the transition region between the two windows is found to be unstable to high‐nmodes.