It is generally assumed in informal descriptions that what distinguishes geminate from nongeminate consonants is duration of articulation. This has not, however, been demonstrated instrumentally, nor are informal descriptions precise about what should be measured. To study the acoustic features of geminates, we investigated geminate stops in Turkish, comparing geminate and nongeminate stop consonants in similar environments. We measured the duration from the beginning of the preceding vowel to the beginning of the consonant closure, the pause duration from the end of the preceding vowel to the beginning of the following consonant, the duration of consonant closure, and the ratio of the rms energy at the onset of the consonant to that of the following vowel. The only significant difference was the duration of the pause. To investigate the perceptual salience of this feature, we took 20 minimal pairs of geminates and nongeminates, cross spliced the pause, and presented a randomized set of words to native speakers of Turkish, who wrote down what they heard. The pause was found to be a significant cue in discriminating between geminate and nongeminate consonants.