The factors governing the efficiency of arylmethoxyacetic acids (AMAAs) for the determination of the absolute configuration of alcohols by NMR, have been identified and their influence studied. The largest Δδ R S values are obtained either increasing the size of the aryl ring (i.e. α-(9-anthryl)-α-methoxyacetic acid, 5), or the population of the most stable conformer (i.e. reagent 3 at low temperature). The use of 5 to induce useful shifts on remote protons of complex molecules (i.e. androsterone) is described.