Speech produced by non-native talkers deviates from native talker norms in systematic ways that reflect the interaction between the talker’s native language and the target language. These deviations result in speech that is almost always easily identified by native listeners as “foreign-accented” and that is typically less intelligible for native listeners than native-accented speech. Determining the contribution of various types of foreign-accented speech features to reductions in intelligibility for native listeners can help advance our understanding of the nature of native and target language sound structure interactions in relation to their consequences for speech communication. This study related variability in segmental production accuracy of foreign-accented speech to variability in overall intelligibility across individual talkers of foreign-accented English who all came from the same native language background, but varied in their levels of English speech production proficiency. The results showed that vowel, but not consonant, production accuracy correlates with intelligibility; and, errors in word-initial position are more detrimental to intelligibility than errors in other positions. These findings provide the basis for a principled and detailed description of the phonetic nature of foreign-accented speech in relation to its communicative function.