Eight cats were trained to localize the source of tonal signals, presented in a free field. Tones of six different frequencies, in octave steps from 250 Hz to 8 kHz, were used. The angle at which an animal's performance was 75% correct was defined as the threshold for minimal detectable angle. This localization threshold was obtained for each cat at each frequency. Across frequencies the localization thresholds changed little from 250 Hz to 2 kHz, then increased greatly at 4 kHz and decreased again at 8 kHz. Similarities and differences in the performance of man and cat in localizing pure tones are discussed in relation to the possibility that the cat, like man, uses differences in binaural time and in binaural intensity as the principle cues for sound localization.