L2 learners’ competence in collocations has drawn increased attention in the field of second/ foreign language acquisition in the last few decades. Yet, further research in different language learning contexts is needed to expand on our knowledge of L2 learners’ collocation attainment. Based on a small-scale cross-sectional study, this study explores the amount and types of English collocations which Turkish pre-intermediate and advanced L2 learners utilized in their in-class writings. The study also intends to identify the mistakes learners made when they produced English collocations. Furthermore, it investigates the influence of the learners’ L1 on the production of L2 collocations. The results showed that the learners’ proficiency level was a critical dynamic determining the amount of L2 collocations produced accurately in essays. The results also revealed that the L1 influence on the production of L2 collocations existed in both pre-intermediate and advanced learners although it varied with the learners’ overall L2 proficiency and with the type of collocation. The study emphasizes the importance of improving EFL learners’ collocational competence in EFL classes to foster their fluent language use in English.