An electromyographic investigation of the internal intercostal muscles in connected utterance together with an analysis of pause placement has been carried out with native and non-native (Asian) speakers of English. A characteristic pattern of muscle activity was found in native speakers. Its essential features were an overall progressive increase in activity throughout the item, localized bursts of activity before commencement of speech phrases, and decrease or cessation of activity with long pauses. The non-native speakers tended to produce repetitive EMG patterns within the one item. Another feature of their utterance was the use of numerous pauses, many of which were inappropriate in placement and duration. The physiological implications of this pattern are discussed. This faulty organization and timing of rhythm units was attributed to the syllable-timed nature of the subjects’ first language, to their method of learning English, and to their lack of experience in speaking English. The internal intercostal muscle activity pattern appeared to be related mainly to the speaker’s degree of linguistic proficie