This thematic issue explores various aspects of interlanguage phonetics and phonology andtheir relationship to general linguistic theory. Research in interlanguage syntax and recently indiscourse and pragmatics has been quite prolific; however, research in interlanguage phoneticsand phonology has produced far fewer studies. Of the nearly 200 articles published inStudies in Second Language Acquisition (SSLA) during the last 10 years,onlyabout a dozen focus on phonetics and phonology. This thematic issue is intended to fill some ofthis gap.