Discriminating between effective theories of U_{A}(1) symmetry breaking

We address the question if one can empirically distinguish between the two proposed solutions to the ``$U_A (1)$ problem'': the 't Hooft, and the Veneziano-Witten $U_{A}(1)$ symmetry breaking effective interactions. Two hadronic observables are offered as discriminants: (1) The scalar ($0^{+}$) meson spectrum; (2) Weinberg's second spectral sum rule. Their present experimental status is discussed.