In this study, the researcher investigated the use of grammatical cohesive devices (conjunctions) in learners' written productions, focusing on Saudi undergraduate students who were studying academic English as a foreign language (EFL). The aim of the study was to examine the use and frequency of four types of conjunctions-additive, adversative, causal, and temporal-in learners' essays. The researcher employed a mixed-methods (quantitative and qualitative) approach to collect data from learners' essays. Textual analysis was the qualitative method employed to identify and count the four types of conjunctions and to determine whether the learners used any cohesive devices incorrectly. This was followed by quantitative data analysis to calculate the students' mean scores and consider significant differences. The data were analysed using Halliday and Hasan's (1976) cohesion framework. Forty female Saudi students participated in the study by writing and submitting essays following explicit instruction on conjunctions. The findings revealed that Saudi EFL learners used different types of conjunctions correctly in their essays, such as ‘and' as additive conjunction; ‘but' as adversative conjunction; ‘because' as causal conjunction; and finally, ‘first', as temporal conjunction. The findings also showed that additive conjunctions were the most frequently used in learners' essays.