  We study the non-perturbative effects of the global features of the
configuration space for SU(2) gauge theory on the three-sphere. The strategy is
to reduce the full problem to an effective theory for the dynamics of the
low-energy modes. By explicitly integrating out the high-energy modes, the
one-loop correction to the effective hamiltonian is obtained. Imposing the
$\theta$ dependence through boundary conditions in configuration space
incorporates the non-perturbative effects of the non-contractable loops in the
full configuration space. After this we obtain the glueball spectrum of the
effective theory with a variational method.
