  We construct exactly soluble lattice models for fractionalized, time reversal
invariant electronic insulators in 2 and 3 dimensions. The low energy physics
of these models is exactly equivalent to a non-interacting topological
insulator built out of fractionally charged fermionic quasiparticles. We show
that some of our models have protected edge modes (in 2D) and surface modes (in
3D), and are thus fractionalized analogues of topological insulators. We also
find that some of the 2D models do not have protected edge modes -- that is,
the edge modes can be gapped out by appropriate time reversal invariant, charge
conserving perturbations. (A similar state of affairs may also exist in 3D). We
show that all of our models are topologically ordered, exhibiting fractional
statistics as well as ground state degeneracy on a torus. In the 3D case, we
find that the models exhibit a fractional magnetoelectric effect.
