The behavior of native English speakers and Japanese English as second language (ESL) learners on word association tasks was investigated. Research has shown that Japanese adults respond in Japanese in an identifiably different way than English speaking adults respond in English, and that native English speaking children demonstrate a developmental shift in word association behavior. It was hypothesized, therefore, that ESL learners would acquire English word association behavior as a function of acquiring English language proficiency. In association to nouns, verbs, and adjectives, significant differences were found between beginning ESL learners and native speakers but not between advanced ESL learners and native speakers for adjectives and verbs. No significant differences were found among the groups for nouns. It is concluded that word association behavior shows potential as an indicator of more generalized language proficiency. (Author/RW)