Chiral low-energy constants incorporate short-distance information from the dynamics involving heavier degrees of freedom not present in the chiral Lagrangian. We have studied the contribution of the lightest resonances to the chiral low-energy constants, up to {O}(p⁶), within a systematic procedure guided by the large-N_C limit of QCD and also including short-distance asymptotic constraints.

PACS numbers: 11.15.Pg, 12.38.--t, 12.39.Fe