Cross-correlation between proton chem. shift anisotropy and proton-proton dipolar interactions is shown to be an important relaxation mechanism. Cross-correlation leads to a partial conversion of Zeeman order into longitudinal two-spin order. The build-up of longitudinal two-spin order can be obsd. selectively by means of a novel expt. that combines double-quantum filtration with two-dimensional nuclear Overhauser effect spectroscopy (DQF-NOESY). [on SciFinder (R)]