Upon consideration of the hydrogen-bonding properties of the NH4+ cation, we synthesized a new class of compounds, M3-x(NH4)(x)CrO8 (M = Na, K, Rb, Cs). These magnetic compounds with the simple 3d(1) ground state become ferroelectric. X-ray studies confirmed that the phase transition involves a symmetry change from I (4) over bar 2m to Cmc2(1) to PI. The transition temperature depends linearly on the composition variable x. The transitions are of the order disorder type, with N-H center dot center dot center dot O bonding playing the central role in the mechanism. Extension of this idea to the introduction of ferroelectricity in several other classes of materials is suggested.