Minimum audible movement angles (MAMAs) were measured in the horizontal plane for four adult subjects in a darkened anechoic chamber. On each trial, a single stimulus was presented, and the subject had to say whether it came from a stationary loudspeaker or from a loudspeaker that was moving at a constant angular velocity around him. Thresholds were established by adaptively varying stimulus duration. MAMAs were measured under both monaural and binaural listening conditions as a function of center frequency (500–5000 Hz), bandwidth (pure tone to 1 oct), velocity (10°–180°/s), azimuth (0°–90°), and direction of motion (left versus right). Preliminary data are consistent with previous observations for frequency and source velocity effects [D. R. Perrott and J. Tucker, J. Acoust. Soc. Am.83, 1522–1526 (1988)]. Data will be compared to static measures of auditory spatial resolution (the minimum audible angle) obtained under the same stimulus conditions from the same subjects. Discussion will focus on whether specialized mechanisms in the auditory system are required to account for dynamic spatial resolution. [Work supported by NIH.]