This study investigated first language (L1) influence on the acquisition of second language (L2) collocations using a framework based on Kroll and Stewart (1994) and Jiang (2000), by comparing the performance on a phrase-acceptability judgment task among native speakers of English, Japanese English as a second language (ESL) users, and Japanese English as a foreign language (EFL) learners. The test materials included both congruent collocations, whose lexical components were similar in L1 and L2, and incongruent collocations, whose lexical components differed in the two languages. EFL learners made more errors with and reacted more slowly to incongruent collocations than congruent collocations. ESL users generally performed better than EFL learners (lower error rate and faster speed), but they still made more errors on incongruent collocations than on congruent collocations. Interestingly, however, the L1 effect was not apparent on the ESL users' reaction time. The results suggested that (a) both L1 congruency and L2 exposure affect the acquisition of L2 collocations with the availability of both maximizing this acquisition; (b) it is difficult to acquire incongruent collocations even with a considerable amount of exposure to L2; and (c) once stored in memory, L2 collocations are processed independently of L1. Possible differences in acquiring congruent and incongruent collocations are discussed. (Contains 2 tables and 2 footnotes.)