Ab initio equation-of-motion coupled cluster (EOM-CCSD) calculations have been performed on a set of 44 complexes to obtain one-bond H-Y spin-spin coupling constants ((1h)J(H-Y)) across X-H-Y hydrogen bonds, with Y as the second-period elements N-15, O-17, and F-19. For complexes with traditional hydrogen bonds, the reduced Fermi-contact terms and the reduced one-bond spin-spin coupling constants (K-1h(H-Y)) are negative. Since K-1(X-H) has been shown previously to be positive, a change of sign of these two coupling constants must occur along the proton-transfer coordinate. For complexes with symmetric X-H-X hydrogen bonds, the two reduced X-H coupling constants are equal and positive at equilibrium. For complexes stabilized by hydrogen bonds that have some proton-shared character, both K-1h(H-Y) and K-1(X-H) are also positive. The signs of all three reduced coupling constants (K-1h(H-Y), K-2h(X-Y), and K-1(X-H)) that can arise between pairs of hydrogen-bonded atoms are interpreted in terms of the nuclear magnetic resonance triplet wave function model (NMRTWM). Determination of the signs of (KH)-K-1h-Y and K-1(X-H) could be useful for confirming the presence or absence of a proton-shared hydrogen bond.