  A boron impurity in silicon binding an extra hole is known to have only one
bound state at an energy of just below 2 meV. The nature of the Si:B^+ ground
state is however not well established. We qualitatively analyze the behavior in
a magnetic field of isolated acceptors in a tetrahedral lattice binding two
holes using group theory. Applying these results, we analyze recent
measurements and conclude that the ground state of B^+ is most compatible with
a non-degenerate Gamma_1 state.
