This presentation documents an attempt to better understand the L2 mental lexicons of a group of English language learners. To explore the relationship between word-association and learners’ lexical development, the researcher employed a psycholinguistic experiment - the word association test, based on Task 123 of McCarthy’s Vocabulary (1990: 152). A simple word association task comprising eight stimulus words was administered. Participants comprised low-level and high-level Japanese English as a Foreign Language (EFL) students and two high-level exchange students from Chile and Finland who were also EFL and English as a Second Language (ESL) learners, respectively. In the study, focus is placed on five types of word relations: contextual structure, (syntagmatic/paradigmatic relations), meaning (sense relations), extra-linguistic (encyclopaedic relations), frequency (collocation), and sound (clang associations). The results of this word association task did not exactly mirror the findings of Aitchison (2003). However, some clear similarities between the two studies were identified. The findings support the claim that the mental lexicon of the L2 learner is highly organized, and that word relations within the L2 lexicon are comprised of primarily semantic or lexical distinctions and not phonological ones.