A project to examine phonetic differences between affricates is in progress. Voiceless palato-alveolar affricates and the most similar stops and fricatives have been recorded in closely matched medial positions from 10 speakers of each of three languages speaking at two different speech rates controlled by a metronome. The languages are (Mexican) Spanish, (British) English, and Italian. Spanish does not have a palato-alveolar fricative; English distinguishes affricate, stop, and fricative; Italian distinguishes single and geminate affricates and stops and has a palato-alveolar fricative. The general hypothesis under investigation is that such differences in the number of sounds which must be distinguished have implications for the ways in which the contrasts will be phonetically realized in the three languages, for example, in the variability found between speakers and between speech rates. Preliminary measurements on durational aspects of the segments examined indicate that there are differences between the languages which can be related to the general hypothesis. [Work supported by NSF.]