Thresholds for the detection of interaural time difference were determined by ten listeners (1) for band-limited random noise (150–1700 cps), (2) for a 1000-cps tone, and (3) for a 1-millisecond click. The average interaural time differences corresponding to 75% correct detection in the symmetrical two-alternative tests were (1) 9 microseconds, (2) 11 microseconds, and (3) 28 microseconds. Ranges of individual thresholds and group psychometric functions are presented.