Purpose: The production of speech sound classes in adult language learners is affected by (a) interference between the native language and the target language and (b) speaker variables such as time speaking English. In this article, we demonstrate how phonological process analysis, an approach typically used in child speech, can be used to characterize adult target language phonological learning. Method: Sentences produced by 2 adult Japanese English language learners were transcribed and coded for phoneme accuracy and analyzed according to the percent occurrence of phonological processes. The results were interpreted relative to a contrastive analysis between Japanese and English phonetic inventories and developmental norms for monolingual English children.