Abstract:The recognition that collocation is an important, yet challenging, variable in second language development has attracted extensive research into how to enhance collocation learning. This study examines the collocational knowledge of Libyan Arabic-speaking learners of English by focusing on the influence of two main factors, the learning environment and the native language (L1), since it has been claimed that these factors affect L2 collocation development. Unlike previous studies on collocations which have largely focused on testing classroom learners, this study compares the use of English collocations by both naturalistic learners and classroom learners to explore which learning environment enhances collocation development more. Thirty-six Libyan learners participated in this study (18 formal classroom learners and 18 informal naturalistic learners); they were asked to complete production and reception tests of English collocations. A questionnaire and a vocabulary recognition task (VRT) were additionally used to facilitate interpretation of the data, by eliciting information about learners' degrees of exposure to informal, naturalistic English and their knowledge of the individual words in collocations. The results showed that collocations are a problematic aspect of language for all L2 learners in the study. However, a naturalistic setting was found to provide a better learning environment for collocation development than a classroom setting. Additionally, the native language of the learner was also found to have an effect on their L2 collocational knowledge. This influence had more of a positive effect on naturalistic learners' knowledge, and a more negative effect on classroom learners' knowledge. The findings also revealed a strong correlation between learners' collocational knowledge and their amount of exposure to informal, naturalistic English.