Experimental results of hard single diffraction and double
pomeron exchange studies at the Fermilab Tevatron p anti-p collider are
presented.  Single diffraction results are compared with predictions from
phenomenological models and expectations from results obtained in
diffractive deep inelastic scattering experiments at the DESY ep collider
HERA.  Double pomeron exchange results are compared with corresponding
single diffraction results to test factorization.