Time-averaged falling velocities of three sizes of spherical particle (d = 8.0, 12.7, 15.9 mm) have been measured in vertically oscillating water. Drag coefficients were calculated, based both on a force balance equation of a free particle in an accelerating fluid and using a measured particle velocity. The calculated drag co-efficient was predicted by a relation obtained the 2/3 - power law of energy dissipation. The experimental particle velocities were compared with the numerically calculated values, and agreement was within 5%.