Measurements of the equilibrium position of levitated, low-density spheres in air were made in a rectangular resonant system as a function of acoustic pressure. Vertical acoustic forces were generated by two opposing JBL compression drivers exciting the fundamental plane-wave mode at 1.2 kHz. Additional acoustic forces in the horizontal plane centered the sample along the vertical axis. The sample equilibrium position is determined by a balance between the gravitational and acoustic forces. A cathetometer measured the sample position to better than ±0.03 cm for sound-pressure levels up to 160 dB. The dependence of equilibrium position on acoustic pressure and sample radius will be compared to theoretical prediction [N. Jacobi and M. Barmatz, Proceedings of the 1979 Ultrasonic Symposium, IEEE Cat. ♯79CH1482-9SU, p. 476]. [Work supported by NASA.]