Abstract: This study investigated how English as a foreign language (EFL) learners' types of language for thinking and types of oral elicitation tasks influence their lexical collocational errors in speech. Data were collected from 42 English majors in Taiwan using two instruments: (1) 3 oral elicitation tasks and (2) an inner speech questionnaire. The study revealed that types of language for thinking affected production of lexical collocations in speaking. Regarding potential task effect, learners had a higher inaccuracy rate of collocation in prepared speech than in the other tasks, with the disparity less than significant. The researchers discuss pedagogical implications for speaking instruction by highlighting the importance of metacognitive strategy training to the enhancement of EFL learners' speaking competence.